[yohui]

For those unaware, "AEB" stands for "Autonomous Emergency Braking". See: https://en.wikipedia.org/wiki/Collision_avoidance_system

Did Tesla cars have AEB prior to Autopilot installation? If not, then this suggests the 40% reduction in crashes may simply be due to the installation of an AEB system. What effect Autopilot's other features may have would remain uncertain.

[greglindahl]

Yes, Tesla cars had AEB since March 2015. Autopilot (with autosteer) came out in October 2015. Presumably Tesla's AEB gets improved a little with every firmware release.

[yohui]

Thanks. But the NHTSA report looks at data starting with "MY 2014" (i.e. calendar year 2013) cars.

If AEB did lead to a 40% reduction in crash rates for Tesla cars, as it did for other car models, I suspect that moving the dividing line by five months later wouldn't change the figures much: you would still have a lot more crashes prior to AEB and fewer after.

[greglindahl]

Tesla was growing rapidly in that era, and the sensors weren't even available at the start of calendar year 2013. All cars shipped with sensors starting in October 2014. It'd be nice if the NHTSA report quantified this a bit, but they didn't. I don't think your suspicion is correct: some of the AEB benefit is in the earlier figure, and the number of airbag deployments is not small.

[yohui]

> Tesla was growing rapidly in that era, and the sensors weren't even available at the start of calendar year 2013. All cars shipped with sensors starting in October 2014.

I don't follow the statement about sensor availability. That doesn't seem to change the fact that all the miles driven "after Autosteer" benefited from AEB, while at most a small fraction of the miles driven "before Autosteer" would have had AEB available.

Given that we know AEB systems do reduce frontal collision rates by 40% for all cars, as the NHTSA report stresses, that implies we cannot attribute the reduction in crashes "after Autosteer" to Autosteer alone.

(Which matters because articles such as the one posted are claiming a cause-and-effect relationship between the introduction of Tesla Autopilot and a reduction in crashes, but if a significant portion or even all of the reduction is due to AEB systems that other cars have also started to adopt then we're mistaking correlation for cause.)

[greglindahl]

I don't believe they counted cars without the sensors, either before or after. Your statement about "at most a small fraction" has no evidence.

Finally, who said the reduction in crashes is Autosteer alone? Not me. It appears to be a combination of AEB and autosteer. That's what "some of the AEB benefit is in the earlier figure" means.

(Edit: note that the above comment was edited without marking the edit. See below.)

[yohui]

> I don't believe they counted cars without the sensors, either before or after. Your statement about "at most a small fraction" has no evidence.

Thanks for explaining. The NHTSA report says:

> ODI analyzed mileage and airbag deployment data supplied by Tesla for all MY 2014 through 2016 Model S and 2016 Model X vehicles equipped with the Autopilot Technology Package, either installed in the vehicle when sold or through an OTA update, to calculate crash rates by miles travelled prior to[21] and after Autopilot installation.

> [21]: Approximately one-third of the subject vehicles accumulated mileage prior to Autopilot installation.

So yes, cars which never had Autopilot installed were not counted, but they obviously did count cars from calendar year 2013 which later had Autopilot installed or else they wouldn't have said "MY 2014".

I don't think it's safe to say that the bulk of the miles driven "before Autosteer" happened between March and October 2015 on cars which had AEB systems available.

> Finally, who said the reduction in crashes is Autosteer alone? Not me. It appears to be a combination of AEB and autosteer. That's what "some of the AEB benefit is in the earlier figure" means.

It's implied by Elon Musk's tweet and all the press articles I've seen that Autopilot/Autosteer is responsible for the 40% reduction in crashes, as I mentioned in an edit to my previous comment.

[mikeash]

Tesla model years match the year of production. 2014 Teslas were built in 2014.

Tesla rolled out AEB in March 2015 as a software update for all cars with the appropriate hardware. All Teslas produced starting in mid-September 2014 have the appropriate hardware, so several thousand MY 2014 Teslas have AEB as of early 2015.

[celticninja]

I don't think it suggests it as much as it can be inferred from looking at both sets of data.

[mannykannot]

Exactly - this is a significant weakness of the study.