Agreed, but they don't need to be. Remember, the magic number here is ~1.4G, for a 1.9s 0-60. The Pilot Sport Cup 2 – a track-friendly R-compound tire used in the webcast car and in the videos – can pull close to that on a skidpad (i.e. less than optimal conditions), meaning the grip is there.
> I think it's straining credulity to believe that an electronic traction control system is going to outperform them to such a huge degree.
Launch control and traction control can make several tenths of seconds of difference, which is critical when you're talking about sub-2s times. Also, traction control can keep the car on the cusp of slip the entire run to 60MPH, which is critical in a car that has a completely flat torque curve and probably enough torque to break the wheels loose at any speed (which is not true for F1 cars).
I also suspect that the Roadster has active damping – another technology disallowed in F1 – meaning that the duration of contact with the road can be maximized. This is important if the road surface isn't glassy-smooth.
> This car also looks to weigh around double what an F1 car will weigh
That doesn't help it at all in cornering, but in a straight line, the increased weight of the car will help it launch even better since it'll increase the traction on the drive wheels (equivalent to downforce at speed).
> Gear changes: F1 gear changes take about 8 milliseconds. A road-going automatic gearbox is definitely not going to beat this.
There's no gearbox to speak of; the wheels are direct-drive. To be fair, this won't contribute significantly to faster 0-60 times, but the gearbox exists to compensate for some less-than-ideal characteristics of an ICE, namely uneven power delivery and physical limitations on peak RPMs. An electric motor has none of these problems.
That's lateral grip, which isn't the same at all. Longitudinal grip, which is what's important here, is very different. There's a lot of clever things you can do to increase lateral grip, such as wheel camber, that don't really apply to purely longitudinal grip, so I'm not sure this is valid.
> I also suspect that the Roadster has active damping – another technology disallowed in F1 – meaning that the duration of contact with the road can be maximized. This is important if the road surface isn't glassy-smooth.
But it has to have (comparatively) extremely soft road-going suspension. I really doubt that no matter how smart the active damping is that it will compare with race springs and dampers. Le Mans cars have all these active damping tricks, traction control, along with slick tires, low weight, very high power:weight ratios, skilled drivers, etc, etc, etc and they still don't get to 60 that quick.
That's an excellent example actually - the Porsche 919 Hybrid LMP1 car has a 0-60 of 2.2 seconds, despite electric power, FAR less weight, FAR better tires and drivetrain [0]. There is just no way you can make a road car that's faster than an LMP1 hybrid. If you can, maybe you can put a roll-cage in and take it to Le Mans.... but I doubt it.
> That doesn't help it at all in cornering, but in a straight line, the increased weight of the car will help it launch even better since it'll increase the traction on the drive wheels (equivalent to downforce at speed).
Weight increases the grip, but it also increases the amount of grip you need - you need more power to maintain the same acceleration, and this power needs to be transferred to the road. I'm not an expert, but AIUI, increased grip due to weight scales linearly, whereas the increase in power required (and thus the increase in grip required) scales geometrically, thus weight is counterproductive in getting you to 60mph faster. I could be wrong about this though - as always I'd be happy to be corrected by someone with more knowledge!
0: https://www.porsche.com/usa/eventsandracing/motorsport/works...
Camber isn't a magical trick to get more grip; it's a way to restore grip that would otherwise have been lost because of uneven tire loading in a corner. In a straight-line drive situation, the load is already ideal; the contact patch is the maximum size and fairly evenly distributed across the width of the tire.
> There is just no way you can make a road car that's faster than an LMP1 hybrid.
Indeed, it's currently impossible to make an all-electric race car that can compete with an ICE or hybrid race car in general race conditions, mostly because of the limitations of the energy storage. If the goal is just for a road car to beat a hybrid LMP1 (or even F1) car in a drag race though, as is the case here, I think that's much more doable. The ICE is really the weak link there.
Mostly. But only mostly. Tire grip is actually really, really, really complex however, and this is one of the places where a simplistic model breaks down really badly. If we were able to model tires with simple newtonian physics, then no car would be able to hold more than 1g in a corner, as at that point the force sideways would be more than the force of gravity holding it to the road. Manifestly this is not actually the case.
Tire grip through a corner is more than just coefficient of friction against a surface. There's a lot of complicated things that happen, but the one I'm going to very lightly cover here is that when you go around a corner your tires deform slightly. The sidewall of the tire is pulled out of place, and at the maximum cornering speed of a tire, it will actually be slipping slightly (which can be heard as tire squeal). Cambering the tire corrects for uneven loading, but it also changes the sidewall stress profile, and thus affects the way the tire deforms under lateral load.
I found a mathematical explanation of some the bits mentioned above here: https://physics.stackexchange.com/questions/5838/why-does-a-... but I haven't checked carefully through it to ensure it's actually correct.
The high-school physics model of grip has them both linear, but more sophisticated models may show a difference.
(Interestingly, more mass on a vehicle does help when it is towing something heavy.)
Electric motors do actually have an uneven response at different RPMs (in the form of back-emf losses). I worked for a while with an electric car team in university, and we used a mechanical system to adjust the stator position and tune the motor for different RPMs. I’m not sure what Tesla is doing to address this (could be mechanical or solid state), but you definitely can’t just keep dumping more power into a motor and expect it to get correspondingly faster, not even as a reasonable approximation.
Edit: the shortest 60-to-0 braking distance I find claimed is for a Dodge Viper ACR (Mk 5) at 87 feet. Assuming constant acceleration, that works out to 1.98 seconds.
[1] http://fastestlaps.com/lists/top-quickest-stoppers-60mph
https://www.youtube.com/watch?v=nAvIVGGhEis
They estimate 2.0s is roughly the limit on standard tires, F1 cars can do it faster due to stickier tires.
He also has a video about Tesla acceleration:
https://www.youtube.com/watch?v=iVGsWvRa1XA
Which talks about whether the Model S has an advantage over the (old) Roadster due to the heavier vehicle gripping better.
Interestingly the number he calculates for a theoretical roadster car is very close to Tesla's new number.
They also have a video about "rollout" which can alter 0-60 times and needs to be taken into account for comparisons.
I'm pretty sure they aren't making it up.
I'm with you for the rest of the post, but this is not straining credulity. Look at the F1 season where traction control/launch control was not yet banned. You can see how the cars with that technology gained a massive advantage. Look no further than some starts featuring Schumacher vs Senna. The former wasn't a better driver, but Senna couldn't do anything but watch him pull away on the starts. And that's 1993 technology.
Now there are minor effects that do come into play, so 100x the weight would be meaningful. But, weight within the range of normal cars is not really important.
F1 tires are nothing like road tires. They're not even vaguely comparable - at normal operating temperatures (over 100C, and they're preheated before starting - although not to quite this hot) they have the consistency of chewing gum. They are also huge - far bigger than a road car could ever hope to accommodate. This car also looks to weigh around double what an F1 car will weigh, and with far, far, FAR less grip, so it simply doesn't seem possible that it can accelerate faster.
To address some of the other replies. Traction control: F1 cars are driven by some of the best drivers on the planet. I think it's straining credulity to believe that an electronic traction control system is going to outperform them to such a huge degree. Gear changes: F1 gear changes take about 8 milliseconds. A road-going automatic gearbox is definitely not going to beat this.
In short - it doesn't matter HOW much power you have, if you can't get it down on the road. Given the limitations of the weight of the car, the limited grip from road tires, and a gearbox that needs to survive everyday use, it seems frankly totally impossible that a sub-2s 0-60mph is correct.