The small overlap test is designed for situations where cars hit one-another, head on, on a narrow two lane road. So making changes only to the driver's side makes some sense here, because it's always the driver's sides that impact in this test. It's less "optimizing for the test" and more "optimizing for results", as these accidents used to be the most deadly type of accidents.

Additionally, this is a really, really difficult test to pass, which is why everyone failed it. Even the revisions didn't help too much because there's not much that can be done to an existing chassis other than add a deflection bar or something. True success here requires ground up engineering.

At last, after a word search of that web page and of the HN comments revealed no glossary-like description of "small overlap" collision, I thank you for your description of it.

It seems like, even if intentional, that it’s a sensible optimization. Among multi-car collisions, drivers’ side small offset collisions I’d expect to be vastly more common than passenger side small offset collisions.

In both single and multi car collisions, we will assume there’s a driver in all cars, but less than 100% chance for there to be a front-seat passenger in all cars.

The question then arises whether they apply those optimizations to the same or to opposite sides in left-hand-drive vs. right-hand-drive markets.

It's very likely. The difference between RHD and LHD models are much more extreme than is obvious. Vehicles have to be designed with chirality in mind, but not everything can just be moved to the other side of the vehicle, for example, a FWD car usually has the engine orientation fixed regardless of market, which is going to cause asymmetries.

You'll sometimes see a real tight engine compartment, with a huge gap where the master cylinder and brake booster will go in the RHD models. I think that the 1990's Camaros and Firebirds had this peculiarity.

It also meant that changing the right hand side sparkplugs was a breeze, but the left side required either dropping the engine or drilling the firewall.

Despite having owned two f-bodies, I never knew they were available in RHD.

Here's one: http://car-from-uk.com/sale.php?id=37485&country=au

I'm not from the UK or any other RHD market, but if you are then are some cars, such as the Camaro/Firebird, sold LHD there? Or just not sold at all?

Looking again at the RHD Camaro I linked, it might be a conversion. The parking brake remains on the right side of the shift lever, and the wipers wipe in the LHD direction.

I'd love to know if there really are factory RHD Camaros, and if not then why did they have that unusually lopsided engine bay.

Additionally, it's probably a reasonable assumption that even in cases where a front-seat passenger is present, the majority of impacts would be driver side.

I thought about the following cases where you might encounter this type of impact:

1. Driver is not controlling the car properly (asleep, drunk, etc.) and leaves the carriageway and impacts some road furniture, etc. - in this case, single driver likely has around 50/50 chance of going left vs right, but an accompanied driver is less likely to have this type of incident (passenger can shout to wake the driver, reach for the wheel, etc.). As a result, total fatalities from this collision mode would probably be significantly higher for drivers than passengers.

2. Driver understeers around a corner. In this case, understeer would be more likely on a smaller radius corner than a larger one. As the drivers' side is closest to the other carriageway, this means that the driver would already need to be on the widest part of the curve in order for the impact to be on the passenger's side. This likely reduces the frequency of oversteering from the outside of a turn - although as a secondary consideration, it probably implies higher speed, and so potentially higher fatality rate. Therefore, as more oversteer-related incidents would happen from the inside of the curve, the driver is more likely to be impacted.

3. Impact occurs during overtaking. In this case, we assume the driver is in the opposite carriageway. Oncoming traffic is likely to evade, and during an overtaking manoeuvre, it is likely that evasion into the driver's original lane is not possible due to other traffic. As a result, both our driver and oncoming traffic are likely to try to evade off the carriageway (onto the hard shoulder, grass verge, etc.) Considering that this is a small overlap test, it would imply that evasion has been at least partially successful, implying reduced speeds, etc. It's probably not particularly more likely that either driver or passenger is subject to this impact.

I couldn't think of any other illustrative cases, but it does seem that the even considering that passengers are not present in all cases, the individual risk to a passenger is lower than the risk to a driver when there is one present.

The article is just flat wrong about Honda.

The small overlap tests started in 2013, most of the Hondas already scored "Good" in the small overlap tests by 2013.

The Author awards BMW and M-B excellent status for correcting their problems by 2017, but most of their cars were Poor/Marginal for 4 years.

Somehow Honda is worse for having most of their models "Good" in 2013 with only a few models having issues.

The Civic and the Accord for example have never been tested as anything but "Good" in these tests, whereas comparing them to the BMW 3-series and M-B C Class those cars tested out as "Poor" or "Marginal" for 4-5 years before they were corrected. The Pilot by comparison did have problems.

How this equates to BMW/M-B being great and Honda being problematic is terrible.

Note the author in his notes doesn't denote which cars/trucks/SUVs in which model years he's actually talking about, making it impossible to figure out how he's judging the brands. Most of doing well on these tests tended to have to do with where in the redesign cycle a manufacturer was with a particular car/truck/SUV.

My understanding is that these companies were gaming the benchmarks, but one possible justification is that many vehicles have only one occupant: the driver. Adding weight and reinforcements for a seating position that's typically unoccupied may seem at least partially unjustifiable.

I agree this seems especially odd since Honda are Japanese and in Japan the driver sits on the right (as they do in the UK, Australia, NZ and some others). I doesn't make sense for them to skimp on driver-side protection in these markets.

Honda domestic models are actually not as ubiquitous as you might think in Japan. They're typically larger than your average kei car; the roads are narrower, the speed limit is lower, and the crash safety standards just aren't the same as other countries.

The current generation Accord went on sale in the US more than 2 years before it went on sale in Japan. There aren't any factories even producing the Accord in Japan. Any of them that exist there are imported. It's primarily a car designed for the US (and other) markets.

The most popular Honda and Toyota models are just as American (or more so) than anything the Big 3 produces. Some of them are even designed in Detroit.