Do you have data to back this up? Unless you're driving a dual clutch "dry" transmission or a CVT, because of Physics, an automatic transmission will always be less efficient. The Automatic transmission Torque converter [1] will waste some of the energy provided by the engine, especially with city driving.

Also, most automatic cars tend to shift gear up too early, and can't switch to gear n+2. Because of this, you spend more time accelerating to your cruise speed. It's well known that accelerating rather quickly to your cruise speed is the optimal strategy for fuel efficiency, hence the reason to switch from 3rd to 5th gear directly.

With a manual, you can also disengage the clutch when you consider it safe (and not slowing down traffic) and you know you're going to have to stop at the red light.

[1] https://www.youtube.com/watch?v=z5G2zQ_3xTc

Two days ago my friend and I were driving a rented car and we've noticed that when coasting, the computer said the fuel consumption is 0, but when the friend disengaged the clutch, the fuel consumption actually went up (!) to some value. We've been wondering what's going on, and we actually suspected a software bug in the fuel consumption indicator. Thanks!

This shifts the engine from combustion, where gas explosions cause motion, to motion causing the engine to turn. Because the engine is still in motion, when the RPM drops below 1500, then engine can resume fuel and begin combustion again.

When you disengage the clutch, the engine is disconnected from the wheels, and requires combustion again to keep running.

Also, on a large, heavy vehicle with a manual transmission, you can get in trouble with misjudging braking time/distance if you only rely on the brakes to slow down and stop. When I have a full load in my pickup (1982 C10) I have no choice but to engine brake as the wheel brakes lose more stopping distance the heavier the load, not to mention it keeps them from overheating and failing early over time.

* 4-wheel braking, even if it is a 2wd car.

* ABS/Traction control systems are designed around brakes, not engine braking.

* Regenerative braking (if equipped) uses the brake pedal

* There is a smooth application of braking power from 80mph to 0mph. Engine braking is indexed (I can only choose which gear), and cannot bring the car to a complete stop.

* The limiting factor with brakes is traction, which isn't improved by using engine braking.

* Using the brake pedal is a single action. Engine braking involves at least 3 (clutch in, shift, clutch out).

* Brakes are cheaper to replace than clutch/transmission.

* Engine braking alone does not activate brake lights.

The only exception is when there is a danger that the brakes will overheat: descending a large hill or hauling a heavy load. The default instinct should be the brake pedal alone.

I wasn't speaking of coming to a complete stop, only of slowing down with the flow of traffic. I should have worded it better, I'm sorry.

> Using the brake pedal is a single action. Engine braking involves at least 3 (clutch in, shift, clutch out).

But if you're already downshifting while slowing down, which you should be, it's actually not extra effort. It's completely natural.

> Brakes are cheaper to replace than clutch/transmission.

That entirely depends on the vehicle and the type of clutch. In my extensive experience (I repair cars on the side, and have done so my entire adult life) the parts themselves often cost about the same. For example, when restoring my Bronco II I bought a clutch kit for $150 and a full set of front brake rotors, pads, and new calipers for about $200.

On my Crown Victoria, which was formerly a police vehicle and therefore has the upgraded heavy duty disc brakes on all four wheels, a shop quoted me $700 for a brake job. The parts alone were $350 through them. Of course I saved a ton by doing it myself, but most people can't or won't do that. The labor for a clutch swap versus a brake job is, again, dependent on the complexity of the vehicle. Most manuals still in use in the US are older model cars, with relatively easy to replace clutch parts.

> The only exception is when...hauling a heavy load.

Which I specifically spoke of. :-)

> The default instinct should be the brake pedal alone.

In an automatic, yes. In a manual, only when needing to stop suddenly or when you've downshifted to 2nd or 1st and you're stopping altogether.

Especially with hilly driving, it gives you a lot more control when slowing down, and you can accelerate straight away since your foot is still on the accelerator pedal.

There's nothing worse than being stuck behind a driver (usually a tourist) in a hilly area who is riding the brakes all the way down.

In my head, using the engine/transmission to "brake" when in gear going down hills or slowing down seems like a bad idea. Something is getting stressed in order to slow the car down.

Having to replace my brakes makes sense, they get worn out, and its relatively inexpensive (especially if I do it myself). I have always been wary of staying in gear to brake. And, as it so happens, my manual has 130k miles on it, stock engine, transmission, and clutch. Never had any problems.

I would love to understand the science behind why using the engine/transmission/clutch to brake is better for the car than just using the brakes.

Clutches get less wear during engine braking because it doesn't slip. When you disengage and reengage the clutch because you're using the regular brakes to slow down, the clutch slips and damages itself.

In the end, the reason for engine braking isn't to reduce the cost of brakes--it's a safety measure that keeps the brakes cool for emergencies & miscalculations, since overheated brakes don't work.

And when you have to change down, while engine braking? (I have an odd learning style. Please don't mistake this for "You're wrong because..." It's a case of "I don't understand why, so...")

A friend once told me that the UK required you to half-engage the clutch while using the brakes and the engine together. I've also read something to the effect of modern brakes are much more efficient so (at least one) UK "advanced driving school" teaches that it doesn't really matter.

I have an older car (1998 Mazda 626 wagon). It's a manual, and when I drive downhill I put it into third and let it coast, braking to reduce speed. Should I be putting it into second, and letting it run up to 3500-4000 revs? Should I leave it in third, and use the brakes? Does it consume more fuel to do this, in a car of that era?

I've often meant to ask my local mechanic about this, but never think about it when I'm there.

The way I shift is as I approach a downhill I keep driving it in gear rather than coast. If its steep downhill, you can brake ahead to lower your speed to something you are comfortable at. Shift down to the gear for that speed and then back off the gas if you need engine braking. You can use brake in combination with engine braking gear if you needs to slow down more than using engine braking alone. I shift down when speed gets lower than in current gear.

That said, I drive a manual and use the engine for braking...

Growing up in the mountains, in Colorado, it was drilled incessantly into me how important it was to use engine/transmission braking on long hills, etc.

I know it, I understand it ... and it always irked me.

I never liked the idea that I would save wear and tear on a consumable that is meant to be regularly worn and repaired and instead transfer that wear and tear to an integral part of the car that is non-trivial to replace or repair.

I would think very carefully about this if I were towing a boat or a horse trailer, but in a normal car it just seems backwards.

It's the reason that sports cars generally come with bigger brakes. Sure, a Toyota Corolla might be able to stop in a similar distance, but things change when you have to do it 5 times in a row.

For most people, it’s not really an issue though.

That condition is known as brake fade/fading and occurs mostly with drum brakes and can occur on bicycles, motorbikes and automobiles.

Braking heats the brake drums, which then expand. The drum may expand in diameter to the extent that the brake pads no longer contact the drum sufficiently enough to slow the vehicle. Your brakes "fade" away.

Many vehicles have disc brakes in front and drums on the rear, an arrangement usually sufficient even in hilly country. Of course when pulling a boat or trailer having all disk brakes would be a safer bet.

Brake drum fade is by far the most common manifestation, but there are other types of "fade", e.g., brake fluid can get heated up enought to boil and reduce braking system pressure, brake pads can "slip" more at extremely high temperatures:

http://bicycles.stackexchange.com/questions/30449/do-mechani...

Last ditch efforts: shift into a lower gear, use any emergency brake (which is mechanical and bypasses the braking fluid system and so won't fade due to boiling fluid), and finally, use the inside of a hill/mountain as a giant brake pad by sliding your car's body into it as gently(!) as possible.

Finally I feel compelled to warn anyone who ever pulls a trailer, boat or RV about a potentially fatal phenomenon they may encounter on even gently sloped roads: undamped driven harmonic oscillation between towed and towing vehicle. My first experience:

VW Beetle towing a U-Haul trailer on a Pennsylvania turnpike mountainside. Traffic moderate in both directions.

On a long downhill segment the trailer hitch began to move to-and-fro left and right, gently at first but, as I attempted to correct with steering, rapidly growing in amplitude. My steering reaction time and corrections were unfortunately timed precisely so as to _increase_ the amplitude of the oscillation. In a flash the rear end of the Beetle was hopping right and left! Insight - I need to dampen the oscillation. I gripped the steering wheel, braced both forearms against my legs and reduced all steering corrections to a minimum (I just kept the car on the road and in the proper lane). The car's front end skidded left and right as I kept the wheels as straight forward as possible. Then I slowly applied the brakes. This brought the oscillations under control and the speed down. I continued the trip at a much slower speed despite the honking of frustrated drivers behind me.

That first experience, enhanced by both impending ignominious death on a mountainside and the sudden realization of the utility of my mathematical physics class* [1], was exhilarating.

In the years since I have myself seen this occur several more times, which makes me think it must be a not-uncommon event that requires some warning.

It once again occurred on IH 10 between Houston and New Orleans, one of the flattest pieces of land in the USA. A heavy-duty six-wheeler pickup was hauling a trailer full of goods on an extremely gentle slope at near 70-mph when his trailer hitch began to oscillate left and right. I had been following and observing his truck and noticed that the system seemed to be periodically oscillating, so I stayed well back and did not attempt to pass even on a four-lane highway. Finally things took a turn for the worse and, within 6 seconds of back-and-forth oscillation and attempts at correction, both truck and trailer were driven off the road into the grassy median. Luckily the median was wide flat grass and no harm occurred to driver, truck or trailer. I stopped and crossed the road as the driver took off his cowboy hat, waved it at his truck and trailer as if dismissing an unruly horse, bent his back, and put his hands on his knees in amazement.

I spoke to him awhile, reassured him and gave as best an explanation to him of what I saw and what he might do to prevent further mishaps. He was quite out of sorts and I'm not certain he was fully able to absorb the lesson. He was definitely astonished to find himself on the median with his truck and trailer turned around 270 degrees from the direction he intended.

Had this happened on a strip of highway without such a wide median the truck would have driven at ~60 mph into ongoing traffic at 70 mph. Had this happened on a hillside, I would estimate a 50% chance of both vehicle and trailer plummeting downhill. For these and other reasons, I think this phenomenon must kill more than a few people each year.

More discussion of fish-tailing trailers:

https://www.google.com/search?hl=en&source=hp&biw=&bih=&q=tr...

Physics can save your life:

[1] http://hyperphysics.phy-astr.gsu.edu/hbase/oscdr2.html - Under topic "Driven Oscillator Example" the red curve describes the ever-increasing amplitude experienced.

https://m.youtube.com/watch?v=SXQt-8SZYT8

It was a fun trip with only a minute or so of harrowing possible death-down-the-mountainside. I'd recommend it to anyone!

Also if the mountain is tall enough the brakes might not make it all the way down which has happened a few times in Norway with catastrophic results for large vehicles like busses.

Suffice to say that they do not recommend against engine braking--quite the contrary. Think about it: the engine is already spinning, so spinning it at a higher RPM for a few tens of seconds does no more wear than accelerating.

The issue is not brake wear--the issue is brake fade, and potentially boiling your brake fluid!

When you're going down a long hill, downshift and save your brakes! It could save your life!

The exact same components that are stressed in order to speed your car up.

Since your engine doesn't have combustion raising cylinder pressures, the total power 'absorption?' under engine braking is necessarily less than the full power output of the engine which the drive train was designed to handle.

The exception is if you have rear wheel drive and enough weight transfer to the front to get wheel hop. But, afaik, this is a problem unique to motorcycles.

https://en.wikipedia.org/wiki/Compression_release_engine_bra...

Engine braking on a gasoline engine is actually quieter than normal operation.

http://www.jacobsvehiclesystems.com/about-us/environmental-h...

As for wear on the engine: the engine is actually designed to mesh with the transmission. Engine braking is not much different than accelerating.

When I was learning how to drive a manual, my Dad was a huge fan of them and all of our family cars were manual. I was taught that it makes a huge difference when you're driving in the mountains to use engine braking instead of your brakes. He also explained the difference in braking in traffic and using engine braking to do so and how it supposedly saves on gas as well - something about idling the engine versus continuing to have the engine running?

I'd be interested to hear from people who regularly drive in the mountains and the advantages/disadvantages of engine braking versus using your brakes and if that was some myth or actually real.

While you're accelerating, you're giving the engine gas to keep it moving and prevent a stall. While braking you aren't accelerating, but you still need the engine to keep going at speed.

If you depress the clutch, it disconnects the engine from the wheels. The engine will then get a trickle of gas (even if you don't accelerate) to keep it moving while the car breaks.

If you don't depress the clutch, the engine stays in connection with the wheels. Their motion drives the engine - the reverse of normal - keeping it moving without burning any gasoline at all.

It's not generally a big difference, but if you're in the hills of Colorado you might care more.

Only if your clutch is so badly broken as to make the car undriveable.

It shouldn't slip if it's fully closed.

(Left-foot braking is a technique where you keep the power down in a bend but dab the brake to adjust the fore-aft balance of the car. It is common in rallying - there is some awesome footage somewhere on YouTube of the driver's feet in an 80s rally car. His feet move so fast it looks like he is dancing on the pedals.)

For reference, I got pretty good at this technique while driving autox, which for those unfamiliar is basically a race course around cones in a giant stadium parking lot, one car at a time. But in my 10 years of driving on public roads, I've never felt the need to use it even once.

Edit: Downvotes? For driving safely on shitty roads? I hope people don't assume Im being a jackass driver just because I use my left foot.

Just because YOU don't see why a feature might be useful does not mean that it isn't useful. It just means you don't see a use for it.

Similarly, while cutting the fuel on break application might be useful or even beneficial in the case of a normal / particularly bad driver (slamming down all the peddles in an emergency) it does mean a drastic change in the human/machine interface. I would say that just like ABS is a good safety feature and airbags / restraint belts are good safety features, the vehicle should CLEARLY MARK these features. Their automation may (EG as in the cases of baby seats) be counter-intuitively less safe in circumstances.

One racing driver technique that can be useful in normal conditions (in a manual) is heel-and-toe braking. I use it to avoid excessive engine braking while downshifting, and sometimes for hill starts without using the handbrake.

Also left foot braking is much more useful day to day than heel-toe. Especially if you ever deal with suboptimal traction. Plus, faster reaction times.

The amount is obviously negligible but it's quite crazy to spend more fuel in order to reduce emissions :)

That is what Volkswagen are being forced to do.

https://hal.archives-ouvertes.fr/hal-01062316/document

Of course, engine braking is obviously more efficient than friction braking, but that's not coasting, that's engine braking.

Another funny note is that "conventional" automatic gearboxes have the highest gear (usually the only overdrive gear) have a coasting clutch on it, so it's not even technically possible to coast with engine engaged. You're always idling if you let go of the speeder, losing energy to the torque converter that doubles as oil pump for the transmission.

   When you coast with engaged clutch, you will engine brake

   Energy doesn't go to the engine for free.
   Adding the fuel to counter the engine braking is less
   efficient than letting the engine run idle while coasting
   due to losses in the power-train

This is also why it is a bad idea to use engine braking with a 2-stroke petrol engine: 2-strokes rely on oil mixed in with fuel for lubrication. When using the engine as a brake no - or hardly any - fuel is added to the incoming air while maintaining high engine speeds, starving the engine of lubrication.

Engine braking is just that, using the engine as a brake. If no fuel is added, pumping losses will make it act as a (relatively weak) brake. If you want to coast without braking, with the clutch engaged, you will need to inject fuel to counter the pumping losses of the engine, losses which are higher if the engine is not idle. Losses in the power train add to the braking effect, which must further be counted with additional fuel.

If you're going downhill with clutch disengaged and maintaining your speed, engaging the clutch will very likely increase your fuel consumption for the same task (maintaining speed). Automatics have a coasting gear (usually the last or only overdrive gear) for this very reason.

(Sorry, I had to do that.)

Side notes: 1. Coasting is not braking. People seem to be mixing "coasting to a stop" and "coasting" in general. Engine braking, when your intention is to reduce your speed, is more efficient than friction brakes, but coasting does not mean that you intend to reduce your speed. 2. Who drives a car with a 2-stroke petrol engine? :)

This is very interesting - thank you.

I shift cars into neutral while going down hills because I strongly dislike the subtle lurching of the hill descent control ...

I never thought I was saving any appreciable fuel.

However, what does happen is that (provided you don't mind speeding) you exit the bottom of the hill with much more stored energy, allowing you to coast (in or out of gear) much further before it is necessary to apply the throttle again.

So it's interesting that the direct effect of coasting in neutral does not save fuel - however I still think the net effect (again, provided you don't mind speeding when exiting a hill) is fuel-saving ...

If that is the only reason for automatic transmission to be more efficient, then i doubt it is.

It's taught for safety reasons. You have more controls of the car with the motor attached.

I remember when I was learning to drive being taught about engine braking (with an automatic) and the tradeoff between using up the brakes or burning fuel.

Well, I own a 911 that says otherwise. It's an older fuel injection system (Bosch K-Jetronic), but it's most certainly fuel injection. Porsche wasn't the only maker to use Bosch fuel injection.

I just don't think DFCO (deceleration fuel cutoff) was a feature of most of the early electronic fuel injection systems. Perhaps it was standard by the time EFI made it to economy cars. I'm fighting a massive urge to go down this historical rabbit hole and read about it, but there's work to be done today.

EDIT: no, it was neither electric nor hybrid car, but some old petrol car with manual transmission (Saab 900 or similar).

-When the clutch is engaged whilst going down hill the wheels turn the engine. No Fuel Required. -When the clutch is disengaged the engine has to turn itself over - which needs fuel.

*Disclaimer, i'm sure carbourettas (sp?) could well be doing weird ass things so whilst conceptually the above holds they may well be different.

Ditto when coasting to a stoplight - with clutch disengaged (or in neutral), it would coast for a longer distance, which - if you're careful and know your vehicle - means you can let up on the gas a lot sooner.

Not calling you out specifically, but a lot of people arguing for manual transmissions in this thread seem to base their experiences on ~10 year old cars or older, and weirdly assuming that nothing has happened since, that software and technology in cars has been magically frozen in time, despite enormous incentives for car manufacturers to improve it.

To test, watch your rpm when you left off the gas, if it drops to ~750-1000 rpm, your torque converter is slipping (as designed) and not maintaining fuel cut.

To agree with you, I think the comments in this thread started from a manual transmission standpoint and then everybody thought it applied to automatics.

In a manual you are burning fuel when the clutch is disengaged to keep the engine turning over. With the engine engaged you steal from momentum which lowers fuel use.

The mid point of keeping the engine engaged and adding enough fuel to reach your desired stopping point once the RPM enters the same range as an idling engine is actually most efficient.

https://www.youtube.com/watch?v=DKfcV7hITYI

https://en.wikipedia.org/wiki/Carburetor

The oldest car I have that has an ECU is from 1987 (although judging the fuel efficiency on that car when it was new is a bit hard since the engine has been completely reworked since then -- including an aftermarket ECU, new injectors, new ignition etc which makes the car a tad more fuel efficient than my 2012 car)

I don't think you need a computer for this: it's called engine braking. https://en.wikipedia.org/wiki/Engine_braking

In the UK you will fail your driving test if you coast, and in some countries / states it is illegal - with good reason.

Just google it - not a single article supporting your argument.

If you're coasting down a hill to a stop, then it's better to coast in gear to use approximately no fuel. If you're coasting down a hill to long level stretch of road it's better to coast in neutral to obtain kinetic energy. If one wants to follow speed limits it's sometimes necessary to first coast in neutral then use engine braking at the bottom of the hill.

The optimal strategy in all cases is actually coasting in neutral with the engine turned off, and then starting the engine when you need to increase your speed. (This advanced technique may be illegal, though).

Apparently Mercedes call it "glide mode" or "gliding mode" depending which bit of marketing you look at. I couldn't find a technical description though (beyond what you already said).

Understandably it is dangerous as you are not in control of the transmission and therefore the wheels, hence the failure in the UK. But I got through some incredibly scarce times by coasting a bit on the commute to work...

With automatics you would need to brake down the hill to stop the car "running away" as it wouldn't engine brake automatically to compensate for gravity's effect.

Most automatic transmissions (or at least the ones I've driven, which arguably is not more recent than late 90s) have low ranges where there is engine braking. That's the exact use case for them. Automatic doesn't (or didn't) mean that you must never shift manually.

Automatic transmissions in large vehicles like trucks and buses usually don't have freewheels either, so there is always engine braking.

Right, but when you're coasting you're burning fuel to turn over, unless you have a perpetual motion engine. Whereas engine braking (on a car with an ECU i.e. one made since 1996 or so) you could be doing 2000rpm but burning no fuel (gravity is turning the wheels which are turning the engine).

... which brakes the car, so you still lose energy.

Can't find literature at the moment, but ISTR that the valve train can take several kW to operate.

Well, of course a hybrid has engine braking - that's kind of pivotal to the whole hybrid design. It freaked my wife out the first time we went down a 7% grade in ours in 'B(raking)' - once the battery charged holding down the brake pedal caused the second MG to disengage from the transaxle and spin at max RPM's to bleed off the excess energy.

But yes, every automatic car I've ever been in has had engine braking as well - going down the same grade by mother will shift her Chevy Impala into '3' and can easily coast down the same hill only applying the brake to turn corners.

Would be nice if our Prius didn't require holding down the brake pedal, but in a way I think it plays into the natural instincts of a driver to do so - but it's a habit that can get you killed driving a manual or standard automatic transmission by overheating the brakes, so hopefully my wife doesn't go down any grades in a car other than our own without me.

Every generation of car is getting better at all these things, so statements about efficiency almost all need a "cars built prior to 20XX".

1. On most automatic transmissions (probably anything newer than the early 90's), the torque converter has clutches inside of it which allow the pump to be directly locked to the turbine. This makes it behave basically the same as a clutch in a manual transmission - no constant slipping. The converter will usually “lock up” once you’ve reached a cruising speed. So, it is less efficient during acceleration, but once the converter locks up, it’s much more comparable to a regular manual transmission. The only thing that still hurts the automatic at that point is the fact that there’s a hydraulic pump which must be driven at all times to maintain pressure to keep the various clutches clamped. So yes, this is where city driving can show some efficiency differences. However, ...

2. On newer automatic transmissions (i.e., transmissions from probably around 2006 and up, such as the ZF 6HPxx series which is found on many Fords, BMWs, and some other brands), the torque converter actually behaves even more like the clutch in a manual transmission in the sense that it’s far more “aggressive” regarding when it locks up. For example, my 2011 BMW will usually lock the torque converter as soon as you take off in first gear (it even sort of feels like when you’re taking off in a car with a manual transmission). Then, it remains locked the entire time after that (even during shifts and wide-open-throttle conditions).

3. Newer automatic transmissions (such as the ZF mentioned above) do in fact have the ability to jump to any gear. I believe this is one of the main things that separate transmissions like the ZF 6HPxx from older style electronic automatics like the 4L80E which use a sprag system. The newer transmissions have a clutch pack for every gear which allows them to jump to any gear rather than following the sequence.

4.I believe that many CVT transmissions still use a torque converter anyway.

2016 Ford Fiesta FWD 4 cyl, 1.6 L - Auto: 27/36, Manual: 27/35

2016 Ford Focus FWD FFV 4 cyl, 2.0 L - Auto: 26/37, Manual: 26/36

2016 Volkswagen Golf 4 cyl, 1.8 L - Auto: 25/35, Manual: 25/36

I think they may be vastly underestimating manual drivers ability to optimize this.

EDIT: Actually on the US site the Auto is rated for 6.9 L/100km, 7.1 L/100km on the manual. The Canadian NRCAN rated it 6.7 L/100km.

The EPA has a standard testing regime, and modern automatic transmissions nearly always score at parity or slightly better than the manual option mounted to the same vehicle.

Interestingly, this is also true for things like 1/4 mile times. "Muscle car" guys hate this, but if you look at the numbers, a modern automatic transmission is both more efficient and more performant than the manual option.

Besides, most manuals are 5 or 6 speed. I was reading about new ZF transmissions and they stated a 14% fuel efficiency gain over a standard 5 speed

I don't mean to be pedantic, but I think your logic is backwards here, ie. It's well known that 5th (top) gear is the most fuel efficient, hence the reason to accelerate to it rather quickly (the optimal rate would vary between cars), I think would be more reasonable.

I don't think the cruise speed factors into it, and neither does switching from 3rd to 5th, unless it's part of the strategy to get to 5th faster.

But then again, I never realised that accelerating harder to get to 5th faster is actually more fuel efficient [1], so thanks for the heads up!

[1] http://www.popularmechanics.com/cars/a6827/6-driving-tactics...

It's a waste of energy and clutch/gearbox actuation to use the in between gears and there's never anything wrong with being in a low gear at any point unless your engine hits the red line.

On most cars fourth gear is really for cruising at a lower speed than is comfortable (or safe) in fifth.

You can also very easily downshift sequentially through the gearbox. Downshifting through several gears takes much more practice to do properly and isn't very useful on the road.

These are of course high-end current model year vehicles, if the tech they have hasn't already trickled down into cheaper cars, it will do so very shortly, making my statement even more broadly true.

From wikipedia : A Lock-up clutch is used in some automatic transmissions for motor vehicles. Above a certain speed (usually 60 km/h) it locks the torque converter to minimise power loss and improve fuel efficiency.

So, as they mention, this transmission is unique. It does, however, not lock up in all conditions - it remains unlocked until you hit 8mph. It sounds like an interesting transmission, but this is not the "norm". All conventional automatic transmissions should be able to do this, although it results in very different wear patterns (brake rings and clutches in the transmission will see much greater wear). It is not quite as interesting as a dual shift transmission, though.

(Having looked at a picture of the transmission, ignore the "combined the best attributes of..." - it appears to be an entirely conventional automatic transmission with a very different operating profile.)

Also, the ZF 6HPxx (and newer) transmissions behave the same way. My 2011 335i will lock up in first gear (probably around 10 mph, but it depends on the load). This transmission has been used by BMW since at least 2006. A derivative of it is also used in the Ford Mustang now.

I'll keep that transmission in mind next time I go shopping.

But indeed, automatic cars are less efficient. They do not know what you will do next, so they often make erroneous gear shifts that waste fuel and time. They don't know when to coast or when to engine brake (For older transmissions, the overdrive gear had permanent coasting, and could not engine brake at all), often have lossy pumps, etc.

Dual clutch transmission are awesome, though.

I saw one accident that the cause was lack of transmission knowing the future:

road crossing, bad road signs didn't made clear who had priority, so both drivers went forward.

Both cars tried then to stop, but the automatic car instead had just shifted up, then as the driver tried to stop, it lurched forward and hit the other car, then it spun and crashed on the wall of a school.

The automatic car was a sports car from the 70s though, so I guess the transmission was even more dangerous.

In a manual, you can of course clutch out as long as your clutch cable (or hose for hydraulic clutched cars) doesn't fail, which is not an option you have for automatics. These kinds of failures do occur today, though. See the famous Toyota "unintentional acceleration" scandal, where a software error read "0% throttle" as "100% THROTTLE GO GO GO GO", causing death in a few cases. There's also a case of a person that was stuck in a car that could not stop, driving at constantly increasing speed on the highways of France, IIRC. He couldn't turn the car off or get it out of gear. You can disengage a manual if you're quick with an intact clutch cable, but you're a bit lost in an automatic, especially if it's too powerful to hold on the brake.

Up here, manuals are normal (with automatics slowly getting more and more popular), mostly because everyone knows just fine how to drive them, and automatics are much more expensive. I, personally, can't decide which I prefer. I'd much rather drive fully manual than a "retrofitted" automatic like the one in a Lupo 3L, and I still have to try a dual clutch transmission, for which I might end up having similar opinions. They always seem to change wrong, the changes are rough and slow, and the clutch engagement is very binary, leading to odd engage/disengage.

I like conventional automatics in cars that haul heavy loads (pushing a 4 metric tonne trailer over a curb in reverse at low speeds without the possibility of gaining some speed first make you worry a lot about your clutch in a manual), and our busses and trucks are generally fully automatic, with more gears than you would bother counting.

The typical car has brakes that can dissipate 4x the engine power, so either the driver failed to press hard enough or the brakes failed in that case.

The other thing these dummies are forgetting to do, in their panic, is to simply turn off the engine.

Reasons that a driver might not simply turn off the engine: 1. Twisting the key to turn off the engine engages the steering wheel lock, which might not be a good idea if you're moving fast. 2. Modern cars with start/stop buttons might end up with issues that disallow stopping the engine - physical button failure, or software issues related to the button handling. 3. Diesel runaway - diesels are quite difficult to stop, as they need very little external assistance, and can run on basically anything. Oil buildup in the intercooler (which any used car will have) that ends up sucked into the intake is a fairly normal way for a diesel engine to self-destruct if you're not quick enough to clutch in so you can keep the engine under control with some load.

Reasons a driver might not be able to hold the engine at full throttle: 1. Brakes seize up at load, and "full power" is certainly a lot of continuous load. 2. Brake failure. 3. The sheer difficulty of holding the car. I have once in my life stopped a diesel van that was idling in first gear using only the brake (long story), and that required a lot of effort. I would not have been able to do it if any throttle had been applied.

That wasn't what happened. People were driving at high speeds on the highway and claiming they couldn't stop. They were wrong.

>1. Twisting the key to turn off the engine engages the steering wheel lock, which might not be a good idea if you're moving fast.

That's why you turn the engine off and then turn the key back on, or don't take the key out. Usually you have to take the key out to engage the steering lock.

Besides, which is worse, accelerating uncontrollably until you reach the car's maximum speed, or killing the engine and not being able to steer?

>2. Modern cars with start/stop buttons might end up with issues that disallow stopping the engine - physical button failure, or software issues related to the button handling.

Wrong. All such designs let you turn off the engine by either holding the button down, or by pressing it multiple times. People just were too dumb to learn how their cars worked.

>3. Diesel runaway - diesels are quite difficult to stop, as they need very little external assistance, and can run on basically anything.

Wrong and stupid. We're not talking about 1960s diesel engines with mechanical fuel pumps here, we're talking about modern vehicles with engine computers and electric pumps. Kill the power and they stop.

>1. Brakes seize up at load, and "full power" is certainly a lot of continuous load.

That's why you press them hard right away instead of trying to modulate the engine power with them....

>2. Brake failure.

Impossible. The odds of having a separate brake failure at the same time as an unintended acceleration failure are astronomical.

>3. The sheer difficulty of holding the car. I have once in my life stopped a diesel van

We're not talking about big diesel vans here, we're talking about regular cars in America which run on gasoline having unintended acceleration problems. Americans do not drive diesel cars, and certainly not diesel vans.

Do you have any more completely irrelevant anecdotes to try to disprove my assertions?

However, this does not mean that people all had the time or ability to stop. Unintended acceleration can happen in many cases, such as in a case of highway driving where, as they try to brake, they notice that the throttle is held. If this happens as someone needs to perform an emergency maneuver, the braking distance will be greatly increased, and they might lose control over car as power is still transferred.

In most cases, it might be very easy to handle the situation when you're prepared, but when you have very little time to observe the problem and correct it, things are less likely to turn out well. You might not have enough time to realize "Ah! My car is not reducing throttle, so I must set the automatic transmission to Neutral!", let alone perform the action prior to collision.

2. The steering wheel lock is different from car to car. My current car (VW) engages the lock when the key is removed and the gear is in "STOP", but my previous cars engaged when the key was rotated counter-clockwise two clicks, making it easy to hit the lock instead of simply stopping the engine. Not being able to steer is quite a fatal thing - see the accidents caused when steering wheel locks were first introduced. Especially when the electric kind was introduced (Chevrolet?), which had problems with spontaneously engaging the lock. This caused people to crash as they were suddenly unable to exit, or enter a turn, with only a second or two to stop the car. On a highway, you ultimately end up crashing into the barrier if your steering wheel lock engages.

3. And how are such designs implemented, if I may ask? Oh, software? Right. Do I need to say more, or do I have to explain exactly why this makes the mechanism entirely untrustworthy?

4. Wrong - you really at least read a bit on diesel engines. First of all, modern diesel engines (That is, 2016 model cars) have two diesel pumps - a low-pressure, electric pump in the fuel tank, and a high-pressure (that is, 1-2000 bars) pump driven mechanically by the drive belt. The electric pump is needed to bring fuel up when starting the car, as cold diesel is difficult to pump, and the starter won't result in significant pumping pressure from the high-pressure pump. However, once started, the low-pressure pump is irrelevant to engine operation, providing only a slight pumping assistance. Killing the engine the "proper" way is done by not opening the injectors, causing the pumps to simply recirculate fuel.

However, this has nothing to do with diesel runaway. During runaway, the diesel engine is not running on diesel, but on engine-oil leaking into the cylinder, often through the air-intake. Modern diesel engines almost always have turbochargers, which leak engine oil into the intercooler once their sleeve bearing, through which engine oil is actively pumped to avoid metal-to-metal contact, have been worn down, increasing the gap between turbine axle and bearing. Once enough oil has built up in the intercooler (which acts as an oil reservoir in this case), you risk sucking it in - and as any diesel engine will happily run uncontrolled on engine oil, this causes engine runaway. This can of course also happen due to other leaks, such as piston or injector seals. The lack of control means you either get to engage a gear and minimize damage as you wait for engine oil to stop flowing into the intake, or if you cannot provide any load, wait for the engine to explode, leaving behind melted pistons in what is now an expensive paper-weight. Remember that a diesel engine ignites fuel with compression (with fuel injected normally injected a full compression to allow for slight ignition timing adjustments, hence the crazy fuel pressure), not spark.

While gasoline engines can also suck in engine oil, they have electric rather than mechanic ignition, and they cannot burn engine oil well enough to run on it anyway.

5. You still need to overpower the engine, even when slamming the brake with all your might. A small gasoline car is probably easy to kill, but a more torquey engine will take quite some effort to stop.

6. Brake failure impossible? What? Brake pipes can burst, caliber piston seals can leak, and regular brake disks seize.

The first two modes of failure usually happen when you apply brake pressure. The more you apply, the more likely that you will break your old brake lines and piston seals. In other words, if your brakes are going to fail this way, they're going to fail when you need them. The dual fluid system of modern cars mean that in some cases, you will get more than one braking attempt (an attempt being a press on the pedal of any kind), but not many, and not in all braking modes.

Brake seizing is of course a possibility, unless you drive around with carbon fiber brakes.

7. Going up to the parent comment - "I am from Brazil", talking about the car reputation there. Feel free to join the comments, but don't try to pretend we're talking about something else now. I don't particularly care about Americans and their poor taste in cars, or your incorrect information about them not driving diesel cars (although they are not nearly as popular as in the rest of the world). Of course, the original post was about American transmission statistics, which are quite unrelated to the engine type.

Do you have any more incorrect or just plain uninteresting comments to try to disprove my assertions, or shall we let it be? :)

Automatic transmissions back then didn't even have lock-up torque converters. You could always stop the car unless the throttle got stuck. The transmission can't suddently send the car screaming forward if the person isn't on the throttle.

On another note, the main automatic transmissions of those days were probably the TH350 and TH400, which actually stands for "turbo hydramatic". That's probably where the name came from.

Browsing fueleconomy.gov looks like that's no longer the case. Looks like the newest versions of the Honda Fit, Toyota Yaris, and Toyota Corolla have better gas mileage with the automatic transmission, for example.

* Mazda 6 2.5L SkyActiv-G MT: 25/37 MPG

* Mazda 6 2.5L SkyActiv-G AT: 26/38 MPG (28/40 MPG in Grand Touring model, not available in MT)

As for the torque converter inefficiency - that is true only for some ancient transmissions. A modern torque converter will waste some energy only during shifting the gears. After synchronization, the torque converter is locked and the connection between the engine and the wheels is mechanical, just as in MT.

"It's well known that accelerating rather quickly to your cruise speed is the optimal strategy for fuel efficiency"

And now - any data to back this up? I don't have hard data, but I have some hard theory. Modern engines have variable valve timing technology which allow them to work in a much more efficient thermodynamic cycle when under light load and low RPMs. When you're not using the full torque of the engine it works in something like an Atkinson or Miller cycle, with high compression ratio and much higher thermodynamic efficiency. A bad thing about Atkinson-like operation (achieved by keeping the inlet valve open longer than normally) is that it reduces the effective capacity and hence power of the engine. So if you press the accelerator pedal fully, the ECU switches the engine to a classical Otto cycle, which is less fuel efficient but gives more power. Hence, if you accelerate fast, your mileage will be worse, not better.

Another issue is that keeping high RPM at low gear (possible with turbocharger running on full pressure) to accelerate fast makes it harder to control burning all the fuel efficiently because there is less time to do that in each cycle. And also the temperature of the cylinders goes quickly up which makes it harder to avoid detonation. So in order to not destroy the engine, the ECU will adapt the injection / spark / valve timings and lambda coefficient to avoid explosive burning of the fuel by decreasing the effective compression-ratio and increasing lambda to decrease the temperature. Lower compression-ratio and higher lambda means lower fuel efficiency.

That's why when I "eco drive", the ECU keeps the gear extremely high, so that the engine works typically in a range 1000-1500 RPM. Now this is quite hard to achieve in practice when driving an MT car, because whenever you want to accelerate faster, you'd have to gear-down by 2 or 3. That's why ATs are better for fuel efficiency.

BTW: I do own 2 cars, one with MT, one with classical hydrokinetic AT, so I have a comparison. I'd really not be able to drive my MT car using such high gears as my AT car can. And also I can't switch gears so fast as an AT can do, even though my AT is not the fastest among all ATs.

Notably, this feels way less pronounced with faster, sporty automatics, which are willing to give you a feel of acceleration and shift more like manual drivers.

Subaru BRZ/WRX manuals have better Milage EPA ratings than their automatic counterparts.

Is there anywhere else where you can get what's supposed to be their high-performance car (my WRX was the year before STI came out) or the performance variant of another (my wife's Forester is an XT), where that automatic transmission is just a 4-speed? And subjectively, it's a rather balky one at that, with very slow shifts.

For comparison, my Genesis Coupe's auto tranny is an 8-speed, which maximizes the time that the engine is at its most efficient. It's also got smooth lightning-fast shifts in comparison to either Subaru.

I think this is widely known fact for modern cars. Automatics (may) have more gears & can consistently shift more optimally than average human driver, making up the loss of "wet" torque converter.

You making that claim based on how automatic transmissions currently work, right? And not on every way they could work.

Purely from logic, your claim has to be false: Imagine a humanoid robot sitting in your driver's seat, driving your manual transmission car, its robot arm doing the shifting exactly as a human would. Your manual car has been turned into an automatic and it is not less efficient.

I suppose you could argue that the robot, being part of the car, has an energy requirement. I would then argue that we could shrink the humanoid robot down to the size of chip with sensor inputs, and replace the robot arm and gear shift with a solenoid or whatever, thereby saving considerable energy.

By this thought experiment alone, I don't see how anyone can make a statement about automatics always being less efficient.

You're forgetting a very important factor: the automatic transmission can only respond to the drivers actions. Unlike the driver it has no knowledge of future plans. It will happily shift up 2 seconds before I hit the brakes because it has no idea I'm planning to take a left turn in 20 meters.

  > It will happily shift up 2 seconds before I hit the brakes because
  > it has no idea I'm planning to take a left turn in 20 meters.

Surely the same data that is used for automatic braking, lane assist etc could be used to improve timings on automatic gear shifts?

I don't think that data is very useful in city driving where most of the shifting happens. No radar or lane detector can detect my intention of taking the next exit on the left.

That being said, I remember reading a piece a while back about a car manufacturer working on linking the car's navigation/GPS to the automatic transmission. So as long as you enter the destination in the GPS it can make more informed decisions.

  > when automatic transmissions are consistently 
  > outperforming humans at fuel efficiency

In a measured test, with a skilled driver, who does the right thing for the entirety of the test, it is most likely that he or she will be more efficient with a manual transmission than with an automatic.

However, in real life, for real humans, over a longer period of time, the drivers with modern automatic transmissions will be more fuel efficient than drivers with similar cars and manual transmissions, because the automatic transmission is a reliable machine that will do the same thing, every time. It doesn't care if you had your morning coffee or not, if some asshole cut you off, or if you got distracted or bored or spaced out and forgot to change your gear to the right one.

And, disregarding the disruption the EVs will be, technology constantly improves, while human skill is fairly constant, so it was just inevitable that automatic transmissions would one day overtake manual transmissions in terms of speed and efficiency. Arguing otherwise is just irrational nostalgia.

I've experienced quite a few humans who, when driving an automatic, seem to select a speed and throttle position that keeps the transmission right at the top of a gear range, with the engine turning much faster than necessary, instead of going slightly faster and letting it upshift. I doubt that's fuel efficient at all.

Even with an automatic the driver has influence on which gear is used, and a driver who naturally doesn't need to know about gearing may unintentionally be telling the transmission, via other inputs such as throttle position and speed, to select too low a gear than what a manual driver would choose.

(For instance, one of my cars has a manual gearbox with an electrohydraulic actuator system and an automatic clutch, operated by flappy paddles. My insurance company says that it is an automatic, while the equivalent of the DMV (correctly) states that it is a manual.)

I drive a manual and I know exactly why it is not fuel efficient: the idiot behind the wheel :-)

My own anecdote is that I'm a better driver in a manual. I'm a lazy driver, and lazy in a manual means avoiding stopping/gear changes by anticipating green lights and so on. Being lazy in an automatic results in more stop and go for me because it's no more effort. I could be as efficient in an automatic, if I put in the effort (which I would probably do if I knew my numbers were going into a study).

Other modern cars have an "eco display" or similar, which gamifies the experience. My previous car had some progress bars for different aspects, and I spent several boring commutes trying to get to a perfect 100%. (I did it once, I was so happy! Usually only got it to 98% before I hit the city and got stuck in traffic again)

Making automatics more efficient is a technological optimization problem. Making manuals more efficient is a human skill problem. I know which side I'd bet on in the long run. (Hint: Not the human)

That has the potential to be really dangerous though, at least where I drive(a third world country). If a car doesn't do what you expect it to when you provide a certain input, that's a recipe for disaster.

Large six cylinder revving to mid-range (say, 7500) with ample torque at all range can drive the car in overdrive even at city speeds, but an automatic will treat most change in throttle as a downshift. Because they have no ability to understand your intent.

I guess self driving car with an automatic can really fix that, especially because they can get geared optimally to the driving inputs the software tells them and they have 'inside brain' information.

I'm not sure I buy this. I noticed when I switched to automatic from manual I would drive in ways I would never have done with the manual because, well, it was easier than having to care about RPM, target speed, and current gear state: I'm not worried about automatic drivers being bad drivers, I'm worried about them not caring.

Here's the site: http://www.autoweek.nl/verbruiksmonitor

The vast majority, certainly >90%, of people who claim to be driving more efficiently manually are simply mistaken.

It's mostly observation bias. They recognize those two situations a day where they really have the upper hand. For a second or two. They don't realize that in most other driving situations they don't even come close.

Day to day driving is wildly different from that, there are only very few situations where people come anywhere close to the maximum acceleration their car would offer. With manual transmission, you can attain submaximal acceleration by flooring the throttle in a low gear. This is much more fuel efficient than getting the same amount of acceleration with a throttled engine at higher rpm. Automatic transmissions make that more difficult or even impossible (depending on implementation).

Worst case: people are unhappy with the acceleration they can get at low rev, because the transmission only allows low rev at throttled state and they don't consider it socially acceptable to rev up. The engine would be capable of much more torque at the desired rpm, if only the throttle could be opened without the transmission shifting for higher rpm. Next time they will get a bigger engine that will be throttled even more. ICE inefficiency rises with high rpm and closed throttle (opening the throttle raises power output more than consumption). Ideal ICE efficiency is when the gear is selected so that torque at open throttle matches the power demand. Manual can come much closer to that than automatic. (Unfortunately, many people don't know that and drive manuals like automatic, e.g. never at really low rpm, never at really open throttle, because they think that opening the throttle would be wasteful)

I'm not going to say "you're wrong" but I think there are plenty of situations where you know or can anticipate what gear you need to tackle a certain scenario, where an auto simply can't know.

For example, a set of 90 degree bends with (very) short straights between them (this is a real scenario where I live and why I've thought about this at length already). In a manual, you might ride the entire set of bends out in a low gear so you get both the most acceleration between bends and not have any gear changes mid-bend so you're ready to accelerate out quickly. An automatic, on the other hand, would be inclined to change up gear between bends and then have to change back down again once you want to accelerate out as it wouldn't really know what was going on.

My car's transmission has a wide variety of options, including a "race" mode, and I usually drive manual instead, because the semi-automatic options seem to be terrible at anticipating anything and coaxing them through throttle alone is an art beyond me.

I know what you mean, the similarity between an automatic and a race driver was only meant to be about the specific context of fuel efficiency, not about shaving of a few more second from your lap times. But in the end, both of those wildly different optimization goals can benefit from a driver's superior ability to anticipate future power demand. And both goals create comparable challenges in "coaxing them through throttle alone", which describes my frustration with automatics pretty well. In day to day driving, people seem to want a certain amount of acceleration at non-aggressive rpm, and automatics that make it hard or even impossible to tap the full low-rev torque of a given engine make people buy bigger engines than they would need if the transmission would better support their use case.

Give me an automatic that allows me to apply unrestricted (by backshifting) torque at any rpm and I would look at it much more favorable.

But note that the transmission in F1 cars is semi-automatic [1]

[1] https://www.formula1.com/en/championship/inside-f1/understan...

Grin. But seriously, at some point, it simply becomes a question of low level control vs improved high level functioning. I love manuals, and drive one, but the writing is clearly on the wall for good reasons. Fortunately, buying a hybrid forces the issue anyway, as others have noted.

I used to code intros in assembler on the Amiga, and did some assembler on UltraSPARC, so the joke is completely lost on me. I love assembler and low level control.

You get mad because your assumptions about your own superiority get placed under doubt by reality and physics? Must be hell of a way to live.

Sounds like a dunning-kruger effect and some anger management issues rolled into one.

Now you're incorrectly assuming that the engineers' and programmers' assumptions about how I drive are correct, and they know better than me. Who are they and what do they know? Who am I and what do I know? What if I'm a professional driver or an engineer just like them, or both? You don't know either of the two parties, so how could you possibly judge this correctly? The answer is - you cannot. You are berating me for challenging what you perceive to be an authority, as if I hadn't studied physics and mechanical engineering and knew nothing about those subjects, and even go so far as to imply I'm incompetent and suffer from an illusory superiority complex based on Dunning-Kruger research.

Is this what we're coming down to nowadays, if someone says "I know what I'm doing, and I don't want someone else to tell me how to do it", they'll be sticker-slapped with a superiority complex? That's the society you want to live in? And that is okay?

Bottom line is: a car with an automatic transmission does not do what I want, how I want, when I want it, and does not drive the way I want and expect it to drive. It fails my requirements, whereas a manual transmission and a dry clutch don't try to meet my requirements or expectations - what I want, how I want it, and when I want it is solely up to me. If I mess up, that's on me as well. It's my problem, my responsibility, and that's great.

As far as I'm concerned, since driving is a very important part of my life and identity, dictating, through the use of transmission or shift points, for example, is attempting to dictate how I live. I, an individual, equate that with someone telling me what I must believe, and what I must accept, "because it's better for me", and this goes against what I believe is my basic right to self-determination. That is one of the reasons I reject the automatic. If I have no direct say in it, then at least I can indirectly vote with my wallet.

Must be hell of a way to live.

I deal with it.

Now DCTs in road-going cars: undeniably automatics.

Probably not for old "3 gear with torque converter" or similiar.

However, it's more convoluted to use. You have to engage the clutch, put the shifter in neutral, and release the clutch again. Compared to automatic where you just have to hold your foot on the brake pedal.

Stop/start reduces fuel consumption on test cycles like NEDC for both automatics and manuals, but I'll bet in the real world the benefit is mostly seen with automatics as many manual drivers will rarely bother to use it.

This is how you should drive if you know you're going to be stopped for more than a few seconds. 'Convoluted' doesn't come into it - it's the default.

Now, when driving stop/start equipped vehicles, I always try to use it. But in a manual, it does takes more thinking and effort and I wonder how many casual drivers actually bother.

The thing is, most of the time you don't really know how long you're going to be stopped for. Will that light take 3 seconds or 30? A manual makes you decide whether to stop the engine, but an automatic just does it every time without having to think about it or perform extra steps. (although, you can override it if you know it's going to be a short stop by just pressing the brake lightly.)

I'm glad start stop is supported on manuals this way. It makes sense. I thought the stop start systems didn't really save much fuel, but I've read some real world tests that clock in at 8~10% savings. All that idle time does really add up.

Now I just don't care about that, since it was too annoying at stop lights, which has led to incidents of auto-stop and immediate start and even a half auto-stop. Didn't notice and bad effects on the car.

If you take a driving test in the UK and do this, that would be a minor fault. You can only have a few minor faults before you fail the test. The rationale is that you need to be in full control of the car at all times, and when you set off you mustn't drift backwards at all. The easiest way to do this without needing three legs is to use the handbrake. Unless you have a diesel engine that has enough torque without any pressure on the accelerator pedal to pull away.

For example if you are turning right and waiting for oncoming traffic to clear, then someone pauses and flashes their lights to let you turn, if you then turn that would be a minor fault in Driving Test conditions - where you are supposed to ignore the driver inviting you to turn and sit like a diddy.

Also you are allowed 15 minor faults before failure, which is quite a lot really.

And now days, newwer cars have the "hill hold" feature which automatically prevents you rolling backwards anyway.

I usually keep my foot to the side, as I was explicitly taught in driving school by a professional instructor to do. And if the master cylinder ever starts to malfunction, since the plate spacing is really tight, keeping the clutch pedal depressed while stopped could prematurely burn up the clutch and the torque plate.

So, it may require more thinking, but I can rest my feet while the light is red and it actually feels good.

Few years ago, I had colleagues who came from a certain foreign country and were not used to manual transmission. They got a company car with manual transmission. The clutch was burned in one month.

A clutch is destroyed by friction - slippage between the two plates that comprise it. This is a useful characteristic when pausing on a hill for a few seconds but I suppose there must be some people that keep the clutch partially engaged for a very long time.

But if you are sitting at a junction with the clutch entirely depressed for a long time the plates are disengaged and no damage is done. That's a bad habit for other reasons, such as if you get rear ended your car is still in gear and could then cause a further accident.

I generally don't. I too have driven several manual pickups, and only once had a squeaky throwout bearing. But I bought that one used so who knows what it had gone through before me.

Some engines are more susceptible to this than others.

Putting the car in neutral is basically one meaningful action - changing gear, yes you have to depress the clutch move the gearstick to neutral and then let the clutch go - but to describe that as "cycle the clutch twice" is madness. Am I missing something?

No madness involved.

(It happens to involve the clutch, but that is "automatic", as in "muscle memory", even though I drive less than once a month)

I would like to know:

1. How long you need to idle to recharge the electricity to battery you use to restart the engine?

2. Does NEDC and others require that the battery has same state of charge at the end of the cycle as when beginning?

Stop/start will automatically disable if the battery has a low state of charge.

It's a pain...and depending on the break, it really may become pain.

Usually if I drive my manual private car, I disengage the gear already on the way to the red light. It just rolls. I break, motor turns off. When I want to start, I push the clutch, motor turns on, off you go.

The good thing is, If I want the motor to launch, I can by pushing the clutch slightly. I can also release it and put my legs wherever I want. I can relax.

Holding one leg constantly on the break is just annoying. For you, your leg and the guy behind you who has to look into that bright red light pointlessly shining in his eyes.

It's a pain...and depending on the break, it really may become pain.

Oh, with an automatic you have the option of putting it in Park also. Certainly, it's a good idea to do that if you're stopped for more than a few seconds. You don't have to keep your foot on the brake, but doing so is enough to activate stop/start.

That's both a long-winded and incorrect way of putting it. If you are stopped, then you're either already in neutral with the clutch released or the clutch is already engaged. There is no other way.

Really, the rule is just "you have to have the clutch released". For experienced drivers of manual transmissions, this is one smooth action.

https://www.fueleconomy.gov/feg/PowerSearch.do?action=noform...

https://www.fueleconomy.gov/feg/bymodel/2016_Mazda_6.shtml

It is fair. When you do motorcycle training for up-to 125cc, you can take a scooter which doesn't have gears, or motorcycle with gear. If you learn how to use gears you know how to ride a scooter, but if you take a scooter, you're not allowed to ride a motorcycle with gears. It's 100% fair, and it's logical.

The bigger issue with scooters vs geared bikes isn't the extra effort of using the gears, it's the much higher centre of gravity and (usually) wider turning circle of geared bikes that complicates manoeuvres. More forward planning is required to avoid tight turns that require high bank angle at low speed, turns that are easy on a scooter. The higher centre of gravity means it's trivial to drop the bike if braking while turning at slow speed. It's easy to hold up a scooter in the same situation.

Of course it is, I was actually talking about UK. Bottom of CBT cert has a line "Moped / Motorcycle", if you have "Moped" ticked and want to ride a gear bike, you have to re-do the CBT on a gear bike.

See item 6 in the table on page 8 of https://www.gov.uk/government/uploads/system/uploads/attachm...

FWIW, I think a staged CBT is a fine concept, especially in London, but there's a risk that an automatic-only CBT would make things worse because of the incentive structure.

In a busy urban environment, focusing on the hazards on the road should be a much higher priority than mastering machine control. Spending time on a scooter is a fine way to adjust to this. Moving on to a geared bike is less problematic as the amount of new input and reactions that need to be dealt with at once is reduced. But a split between auto-only and geared CBTs would probably push more riders to go geared sooner rather than later (to avoid prematurely limiting their options), and increase overall risk on the road. I think this is part of the reason for the prevalence of geared cars on the roads in the UK.

On the other side, if you learn to ride out in the countryside, there's no guarantee you'll be any good at handling the hazards of rush-hour metro traffic.

I've never heard of a situation where a person harmed themselves or others because they tried driving a manual transmission without knowing how to do so. People who don't know how to drive them simply don't drive them for one of two reasons: 1) they are too scared to try 2) they can't make it more than 2 feet without stalling.

My sister and I both acquired licenses with automatic transmissions and eventually owned manuals. Being required to take a new test to acquire a new license to manually control the transmission would have been impractical and annoying.

Personally, I think it's a silly restriction. I learned gears on my own, if you know how to ride a bike it's not complicated to pick up - even in the CBT training they expect learners to pick it up in a half hour or so.

Braking wastes the most gas.

Turns out they used cruise control for most of the stretch, which I never used, and it was often the difference of 3-5 gallons over the course of the trip. Not a huge deal, but $4 gas did influence it a bit.

Cruise control was significantly worse than driving it normally, at least when I was at the wheel.

The route is a very hilly one, so I somewhat suspect it's that the cruise control was not very good at knowing when to accelerate and when to coast.

My 2007 Civic doesn't account for incline when doing cruise control. It has some sort of lookup table that says, "When the owner sets me to 65 miles per hour, I go at this RPM." If I keep slowing down because I'm on a hill, it downshifts a gear and accelerates hard until the car goes back up to 65 miles per hour. Wash, rinse, repeat. I always disabled cruise control on hills because of it.

My fiancee's 2014 Nissan Rogue accounts for hills with cruise control, and it never has these intervals.

She drives a minivan with a V8 and uses every bit of it on winding Massachusetts roads. People who haven't grown up with it get carsick.

She's a damn good driver - in 10 years, she racked up about 430,000 miles in a Toyota Sienna without an accident... but holy fuck she's traumatizing to ride with.

At first I thought it was a mistake almost like the engine was lugging but it was in eco mode and shifting early.

In normal mode it can shift through three or four gears in (what felt like) one second. And it has a seven speed transmission.

I was wondering if I got a Hellcat trans by mistake!

When you're on the highway in cruise I'm sure it selects a ratio that gets the best possible milage, but they live in the country. You need to accelerate through tight turns, pass slower vehicles without hitting oncoming traffic and constantly adjust the throttle and steering on dirt roads based on conditions. Driving in the middle of nowhere is a very active process and it always feels like that car is just in the way.

Just a tiny bit of throttle causes it to downshift 2 or 3 times and rev the nuts out of the engine when all I wanted was just a little more torque. Lifting off just a little to prepare for a tight bend upshifts to engine brake, so once you're halfway through the corner and want power to accelerate through now it has to downshift 3 or 4 times to get the revs back up. It feels like I am constantly at war with the transmission trying to get it into the right gear and then stay there. It's the most indecisive codriver I've ever experienced.

One other thing about the van it's so sluggish off a dead stop it's as if a normal press of the throttle does nothing a tiny bit more you're spinning the wheels and massive torque steer.

I've ridden with people that drive like that. Self-driving cars can't come soon enough.

I just found it funny that brake jobs on that poor minivan always cost shitloads of money because she always ground the pads all the way down to the metal and obliterated the rotors. I'm sure that the mechanic always sighed and shook his head ruefully at her.

When I took my fiancee home to meet the folks, she made her carsick. I found this hilarious because I'd grown up with it, so it was completely normal for car rides to be ZOOM-STOP-ZOOM-STOP the whole way.

For the record, I drive like a grandma.

As for eco-driving, I was told in no uncertain terms by the guy who examined me that if I tried to drive as eco-friendly as the official course material suggested, he'd fail me for being a hazard to other traffic.

Seriously, his (valid, IMHO) point was that driving eco-friendly was all well and good when conditions allowed (A distinction not being made by the training manual) - but when interacting with other drivers, accelerating slowly, for instance, would often mean you could never (legally) enter a road where you're required to yield.

The Norwegian definition of yield being that you should in no way impede on the operation of the car with right of way - in theory, if you're entering a road with right-of-way and a driver already on it has to ease up on the throttle pedal even for an instance to maintain safe distance, you're breaking the law.)

https://www.admin.ch/opc/de/classified-compilation/19580266/... (German)

He told me I was a bit slow changing gears, but fine at anticipating when I'd need to stop.

My VW has this. It's useless, I never look at it. It is very simple and clearly intended only to give the best results on the controlled gas mileage testing - I believe that if a manual car has a gear-change indicator, the EPA test drivers are supposed to follow it. The advantage of a human selecting gears is that they can use more information than just the speed and engine rpm; for instance there is no point shifting into 6th gear if you see a big hill right in front of you. It also never indicates for the driver to skip a gear. Maybe you will save a few bucks on gas if you follow the indicator religiously but you'll probably break even after you have to replace your clutch early.

I agree that it is imperfect, and imo annoying/distracting. But it may work for a large number of drivers, most of the time.

I would rage in traffic if I had to do "clutch, neutral, cluth, first gear" mantra for 20 minutes to move a little in traffic - releasing break pedal to crawl a bit and then pressing it again to stop is a god send after driving manual for 6 years. :)

Manual is good for 300+ bhp weekend cars, not daily use cars.

Interesting. German driving schools actually explicitly tell you to downshift before overtaking so that your acceleration is higher and you spend less time in the "wrong" lane.

Take a look at official car manufactures tables, in most cases automatic is less fuel efficient, cars where it is more efficient (at least according to the manufactures) are not as common.

Automatic gear suggester makes the suggestions based on the revolutions and if you know what you are doing (takes a little practice and understanding), is always late. Manual transmission gives you more control over revolutions. This could also mean more fun driving. You can also use your engine for slowing down etc. The same could be done with robotic transmission, but that is usually more expensive to have and you do not get to control the clutch release.

Besides, you gain better motor control of your body as a bonus.

Next car I'm getting, which is soon, is going to be an automatic if my plans turn out well. For some car models its very hard to find manual gearboxes, for example Kia Sorento manual is unusual. I assume its the more expensive car, the less likely it is to have a manual tranmission.

Manual transmissions are also typically lighter which also results in an efficiency gain.

If you prefer an auto that's fine, you're in a huge majority. But the idea that they are more efficient than manuals is factually wrong.

If you run across an individual model of car where the EPA estimates give an advantage to the auto that is because of gearing and nothing else. That tells you the manual transmission was given much more aggressive or "sporty" gearing, probably starting with the final drive ratio.

But that's a rare situation.

I would never want automatic transmission for my car, it's inferior, expensive, less fun and car has no way knowing details of road situation I am facing and choices I am about to make. And I am far from petrolhead person FYI.

Another point - I don't know a single person who has automatic gearbox in their car, not even soccer moms.

Automatic gearbox is faster, and probably better for complete novice drivers so they can focus more on situation on the road. That's it. It is more costly, will wear engine faster, removes some connection between driver and car (includes fun of driving, but not only). Plus it creates desperate and sometimes dangerous drivers when they sit in a car with manual, which will almost inevitably happen.

And yet you didn't refute a single one of them, and only offered subjective preferences and personal anecdotes.

You like driving a manual. Bless your heart. Modern automatics still accelerate faster and are more fuel efficient than manuals. Just take a look at what the car manufacturers themselves report.

Automatic transmission 'learn driver habit' multiplies the above, and yet everybody in this discussion ignores it. CVT comes closer to efficiency of manual, but it's not popular because "the car just doesn't have the power on demand dude".

This subject is a horse beaten to death, and then to a pulp, where people that have sporadic and rather incomplete knowledge, write novels based on what was on the car sale pitch.

https://www.fueleconomy.gov/feg/bymodel/2015_Scion_FR-S.shtm...

Now, perhaps this doesn't accurately represent real world driving conditions but nonetheless, physics notwithstanding, it does suggest that an automatic can be more efficient using standard measurements.

I see two explanations for this:

1) They're all lying

2) Technological progress has finally caught up to a system that is bounded by human skill and hand-foot-coordination.

(I'm betting on technology, are you betting on the human?)

All other points I mentioned - you don't care about neither. Just bashing swedish system because you don't like it from you own personal view (if you cannot skip gear and whine about it, you are complete beginner, there ARE good reasons they have it and it happens in real world). My opinion might be biased since I always drove manuals for my own car, and rental automats have been consistently horrible/mkay boring at most (this includes latest Porsche and Ferrari 458 btw)

    > it's inferior, expensive, less
    > fun and car has no way knowing
    > details of road situation

Food for thought.

As a manual driver I can potentially screw up fast acceleration from a still-stand, e.g. when needing to do a quick merge with pretty bad consequences.

I've also noticed that my shifting is very tuned to the weight of the people normally in the car, I choked the engine twice when on a trip with friends and a full car. Embarassing and potentially dangerous. Note: more than a decade experience on manual.

Interesting. Here in New Zealand, once you move from your learners license (fully supervised driving) to restricted (ability to drive by yourself with conditions), if you sit the test in an automatic you get a condition for automatic only on your license. Once you sit your full license in an auto, that restriction disappears.

Even to this day it's probably hard to beat a good manual driver for eco perf, but perhaps average drivers do at least as well with a modern automatic.

But the car market is also changing. We are (regarding cars) a diesel country but as the government want to promote (as they are less polluting) petrol and electric cars, the taxes are becoming a lot higher for those who want to drive with diesel.

If I'm not mistaken (not a car enthousiast) diesel cars with automatic shifters are rare. So when diesel is out, it may also change in this department.

Pretty much any European diesel executive car (Mercedes E-class, Audi A6, BMW 5 Series) is equipped with an automatic.

This is because with a stick-shift you can just gear down when going downhill or before a foreseen stop and let the engine do most of the breaking for you. You then only use the brakes to bring the car to a full-stop on the last couple meters. This gets you much better mileage on your brake disks and pads. Can't do that with an automatic.

Plus it's more fuel efficient.

As someone who preferred cars with a manual transmission until recently, the paddle shifters are useless when accelerating (they just don't work well, and rarely feel "smooth"), but I really appreciate them for engine braking in the snow.

I wonder if you could get similar brake-saving results if you got accustomed to switching to manual mode when braking and then switching back to drive regularly.

Unfortunately it seems a lot of drivers don't know about it.

E.G. you're in fourth gear at 50 MPH, you engage the clutch pedal, shift to third, tap the gas, and release the clutch pedal.

I think the misinformation could be an historical artifact from times when automatic transmission technology was in early stages.

I find the shift indicator annoying. Depending on the car (e.g. my diesel 1.6L), it will probably be unreliable. One example is suggesting to shift up when driving on a light ramp when going over 2000rpm - this might be more eco, but it will put strain on the engine and also decrease your reaction time if you need to accelerate.

The only useful thing that the indicator does convey is to keep it between ~1200 - 2000rpm and don't go over 130km/h if you want to save fuel.

Interestingly my car model has the best fuel efficiency available only on manual, the same engine automatic uses slightly more fuel. But an automatic is generally safer (instant reaction time) and less troublesome (can't choke the engine). I don't think one has any chance of doing things like controlled drifts with an automatic.

I love manuals, but I have to acknowledge modern automatic transmissions are very well executed.

The only AT cars that I know have better fuel economy than good manual drivers are cars with CVT (continuously variable transmission). They are expensive and not something I would fix myself though :)

They won't decide the issue as they have no transmission, they are option number 3 so to speak.

Governments aren't exactly famous for being completely up-to-date on everything. The driving handbook you're complaining about was probably written 30 years ago... Back then, automatics really did suck badly.

With modern cars, automatics do get better fuel economy than manuals according to all the official fuel-economy tests I've seen. One big difference between the two that I've noticed is that in automatics, they tend to have taller gearing overall, and cruise at lower rpms (because of a taller final gear). This is most likely because it's so fast and easy for an automatic to downshift when it needs to, unlike a stick; this is especially important when using cruise control on the highway. The main problem with automatics (but not DSGs like VWs have) is the inefficiency of the torque converter. But modern automatics have worked around that really well with TCs that lock up and unlock very readily, so they're really not much different than a manual with its slipping clutch.

Luckily, here in the US, for all the things we do wrong with cars and drivers' licenses, there's no automatic restrictions I've ever heard about. I've heard of some states having such a thing on their licenses, but in reality I've never heard of them actually sticking that on someone's license if they took the driving test in an automatic. Almost anyone is allowed to jump in and drive a stick any time they want.

No, it's continually updated, and featured lots of other modern facts about cars. For example, from a safety perspective, it urged people to stay the fuck away (maybe not using those words) from cars manufactured before 2000, because safety ratings increased a lot between 1990 and 2000, across the whole board.

The eco-driving requirements are 10 years old, at the most, but the manual still states facts about automatic transmissions that were true 30 years ago.

It's also important to remember that getting a license in European countries is generally a lot harder than in the US, so the eco-driving requirements results in people having to spend time learning the "theory" behind it, spending valuable driving lessons with an instructor to learn it, practice it, and getting evaluated on it during your final road test, and failing to drive "eco-friendly" will result in you failing the test.

So it's a big deal, it affects a lot of people, and it's mostly been obsoleted by technology. The gains from forcing people to learn eco-driving are minuscule, and the whole piece of shit could be replaced with one simple sentence: "Please buy a modern car". The last 10-15 years have seen crazy efficiency gains, and buying a new car will do more for the environment than a lifetime of eco-driving in an older one.

And that grinds my gears. :-)

> Almost anyone is allowed to jump in and drive a stick any time they want.

Fortunately that is pretty self-regulating, because it's incredibly hard to drive a manual if you haven't had practice and training. :-)

Exactly. Why bother regulating this at the DMV when people who can't drive a stick simply aren't going to try anyway (unless they're trying to actually learn and a friend is teaching them)?

That's weird about the handbook. You're exactly right: if you want to drive economically, the easiest thing to do is simply buy a newer car (and of course do things like not do full-throttle acceleration from stoplights, but that applies equally to all cars). Automatics in the last 5 years have surpassed manuals.

From my empirical experiments, and from understanding how modern automatic transmissions work, the assertion above is incorrect, and here is why:

a modern automatic transmission is controlled by firmware, a unikernel. The shift points and the shifting logic are based on the developers' very dim understanding of economy and of performance driving, and because the firmware is so shitty, there is often a significant latency involved - by the time the unikernel has managed to process all the inputs from all the sensors, compute a decision and acutally shift the gear, I've long since shifted with a manual. On top of that, the developers' opinions of what's acceptable and what makes sense are truly dim and utterly infuriating: as I drove the manumatic in hypermiling mode in which I normally drive a stick, the idiotic unikernel refused to upshift because the programmer thought that the gear would be too high and the RPM's too low, neither of which was the case. This was a 3 liter V6, so with plenty of low-end torque for the situation I was putting it through.

Incensed, I repeated my experiment on other makes and models: the result was always the same.

After so many years of automatic frustrations, I will never again own one: the day when I'm no longer able to buy a vehicle with a manual transmission is the day I take a bicycle or walk with the two legs nature gave me, or engineer my own car, and the car manufacturers can go to hell, because they sure won't be seeing any of my money ever again.

Much better to have the driver (regardless of human or software) control both transmission and the other concerns.

> a modern automatic transmission is controlled by firmware, a unikernel

Have you seen the source? If not, how do you know it's a unikernel?

> The shift points and the shifting logic are based on the developers' very dim understanding of economy and of performance driving

"dim understanding"? Do you have a reference for any of that? Why do you think it's developers, not mechanical engineers or engine testing that resulted in the shift threshold?

> there is often a significant latency involved - by the time the unikernel has managed to process all the inputs from all the sensors

Again, that's a heavy assumption unless you have a source for it. Also, from own experience in actually writing control software like that, real world sensors can be read tens/hundreds+ of times per second. But even with tiny 8K microprocessors you can process it more quickly. Mostly you sit in a tight loop and wait for new data. Processing it takes tiny fraction of the wait time.

> On top of that, the developers' opinions of what's acceptable and what makes sense are truly dim and utterly infuriating

Yeah... you're just throwing ad-hominem around. Please come post some sources which support your opinions.

More to the point, the sensors are either wired directly to the controller or data is retrieved over CAN. And there may not even be a spin-lock waiting for that data, data acquisition could very well be interrupt-driven.

The latency claim is totally unfounded, and anyone who has made use of an embedded platform (even as weak as PIC or Arduino) to collect data can see it as totally and utterly wrong.

Where is the latency coming from, then? Other than disputing what I wrote, no explanation of where the latency is coming from has so far been offered.

I will gladly accept an explanation where the latency is coming from, and have even listed concrete models, years, and scenarios to facilitate a concrete explanation. Please, have at it.

Please show some emapthy and think about how the code could be improved instead, so these criticisms can be addressed with a practical solution.

In this particular case, all my criticisms can be addressed by offering a manual transmission option with a dry clutch, not even code optimization is required.

Also, as a firmware writer, you know that all such source code is under strict non-disclosure agreements, and whatever I know or have seen, I wouldn't be at liberty to discuss or cite, or else I risk legal penalties. We're neither anonymous nor protected here.

As for unikernel, any firmware or subsystem concerned with one task - such as running a vehicle - is by definition a unikernel - all firmware is, as its running one single monolithic application image.

Developers versus mechanical engineers - in this context a mechanical engineer is also a developer, just of the transmission, and they often write the software themselves, too.

Finally, as a firmware writer, please explain to me why there is a lag between depressing an accelerator pedal in a 2011 Volkswagen Golf, why the engine will often konk out unless the accelerator pedal is pressed fully when starting on a hill, and why a 2012 Buick LaCrosse will display "shift denied" on the dashboard when I try to upshift from 5th to 6th going at 1,400 RPM, which would put me at 1,200 RPM, well within the engine's ability to continue running efficiently?

Well, doesn't fuel flow need to be increased before acceleration can begin? That causes latency, much more than software would. Perhaps the software is causing a little bit of that, perhaps there's a simple delay loop instead of a sensor there and it's a little too long.

We'll never know, but there are plenty of guesses you could make.

> why the engine will often konk out unless the accelerator pedal is pressed fully when starting on a hill

That doesn't at all sound like a software problem. It sounds like you're conflating "I don't like my car" with "my car software sucks".

> upshift from 5th to 6th [...] 1,400 RPM [...] 1,200 RPM

Are you certain that upshifting like that would only drop you 200 RPM? Not at least 1000? I'm fairly certain that's not correct.

> [...] all my criticisms can be addressed by offering a manual transmission option with a dry clutch [...]

Just buy a manual car if you care so much. Or buy a journal and vent into that rather than the HN comment section. Goodness gracious.

No, because the engine in question is a common rail diesel engine, which means that the fuel is kept under a constant pressure of 2,200 atmospheres, ready to be injected into the cylinders. The only thing that has to happen is for the piezoelectric injectors to open. On a vehicle with a common rail diesel engine without firmware, where the logic is hardwired electronics in the ECU, and the throttle is connected with a cable as opposed to drive-by-wire, such a thing does not occur: zero latency, instant response.

As I owned both types of vehicles, I was in the unique position to observe and experiment. These are vehicles from completely different manufacturers, one German, one Japanese. The Japanese diesel has no issues or problems whatsoever. That's the one I kept.

Not a single stall since going back to a mechanical throttle. And also, I've learned on a manual and have been driving them daily for decades.

And for the record, I had two firmware updates on the drive-by-wire model, and they only helped marginally with throttle response, but never fixed the issue.

You literally said it's due to developers' dim opinions. Lots of people don't like auto transmissions, and that's fine. Just chill about it.

> you know that all such source code is under strict non-disclosure agreements

Nope. Are you saying that all such code is under strict NDA? Likely, you can still say you signed one and cannot talk about it if that's the case.

> I wouldn't be at liberty to discuss or cite

As in, you cannot link to an existing, public article that supports what you're talking about? I call BS.

> any firmware or subsystem concerned with one task - such as running a vehicle - is by definition a unikernel

That's not a definition of a unikernel. You can easily have embedded systems with no kernel to speak of. It may be a unikernel, but since you're possibly under NDA you're not saying that, are you?

> Finally, as a firmware writer, please explain to me...

I'm not a the author of those systems, therefore I will not make assumptions about them. And I recommend the same to you.

What you're describing is behaviour and sure - they may behave like this for some reason. Blaming that on a specific part of the system, or technology, or developers that are dim and do stuff without a reason, without a good proof is neither useful nor helpful.

I did, and I stand by what I wrote: the product is bad, no matter how you slice it and dice it! But to label a generalized categorization based on anecdotal yet empirical experiments as ad hominem is outrageous. In my view, that is wanton abuse on equal grounds with censorship and other repressive measures, just because someone on the Internet doesn't like what someone else on the Internet wrote.

Lots of people don't like auto transmissions, and that's fine. Just chill about it.

That is a very personal issue for me, because driving is a physical and mental activity that I undertake intensely every day, and take it way more seriously than the average person. If I could chill about it, I would not have commented in the first place. But if one does not report what's broken, it will never get fixed:

"we can't fix it if we don't know it's broken."

Now, I don't mind having that choice, but when it means that it messes with my capability to choose a manual, because none is offered, that is where I have a major problem. If people want to drive automatics, I don't like it, but it's their choice and in general I don't care, as long as I can have my choice available, a manual. Live and let live. However, the situation is not developing in that direction, quite the opposite.

You can easily have embedded systems with no kernel to speak of.

Any firmware is an unikernel unless it is running as a generic operating system with generic processes and running multiple, distinct applications, or capable or running more than one single application. Otherwise, if the firmware is one single image running as one single monolithic body of code, they are one and the same. BIOS firmware, for example, is a unikernel. OpenBoot PROM is a unikernel. ECU firmware is a unikernel.

It may be a unikernel, but since you're possibly under NDA you're not saying that, are you?

Okay, you got me. I may not say anything. Well played, well played, I salute you.