Tuesday, December 19, 2023

Take Tesla safety claims with about a pound of salt

This morning when giving a talk to a group of automotive safety engineers I was once again asked what I thought of Tesla claims that they are safer than all the other vehicles. Since I have not heard that discussed in a while, it bears repeating why that claim should be taken with many pounds of salt (i.e., it seems to be marketing puffery).

(1) Crash testing is not the only predictor of real-world outcomes. And I'd prefer my automated vehicle to not crash in the first place, thank you!  (Crash tests have been historically helpful to mature the industry, but have become outdated in the US: https://www.consumerreports.org/car-safety/federal-car-crash-testing-needs-major-overhaul-safety-advocates-say/ )

(2) All data I've seen to date, when normalized (see Noah Goodall's  paper: https://engrxiv.org/preprint/view/1973 ) suggests that any steering automation safety gains (e.g., Level 2 autopilot) are approximately negated by driver complacency, with autopilot on being slightly worse than autopilot off:  "analysis showed that controlling for driver age would increase reported crash rates by 11%" with autopilot turned on vs. lower crash rates with autopilot turned off on the same vehicle fleet.

(3) Any true safety improvement for Tesla is good to have, but is much more likely due to comparison against an "average" vehicle (12 years old in the US) which is much less safe than any recent high-end vehicle regardless of manufacturer, and probably not driven on roads as safe on average as where Teslas are more popular. (Also, see Noah Goodall's point that Tesla omits slow speed crashes under 20 kph whereas comparison data includes those. If you're not counting all the crashes, it should not be a huge surprise that your number is lower than average -- especially if AEB type features are helping mitigate the crash speed to be below 20 kph.)  If there is a hero here it is AEB, not Autopilot.

(4) If you look at IIHS insurance data, Tesla does not rate in the top 10 in any category. So in practical outcomes they are not anywhere near number one. When I did the comparison last year I found out a new Tesla was about the same as my 10-year-old+ Volvo based on insurance outcomes. (Which I have since sold to get a vehicle with newer safety features). That suggests their safety outcomes are years behind the market leaders in safety.  However, it is important to realize that insurance outcomes are limited because they incorporate "blame" into the equation. So they provide a partial picture. IIHS Link: https://www.iihs.org/ratings/insurance-losses-by-make-and-model

(5) The NHTSA report claiming autopilot was safer was thoroughly debunked: https://www.thedrive.com/tech/26455/nhtsas-flawed-autopilot-safety-study-unmasked 

(6) Studies that show ADAS features improve safety are valid -- but the definition of ADAS they include does not include sustained steering of the type involved with Autopilot.  Autopilot and FSD are not actually ADAS. So ADAS studies do not prove they have a safety benefit.  Yep, AEB is great stuff. And Teslas have AEB which likely provides a safety benefit (same as all the other new high-end cars). But Autopilot is not ADAS, and is not AEB.
For example:  https://www.iihs.org/topics/advanced-driver-assistance  lists ADAS features but makes it clear that partial driving automation (e.g., Autopilot) is not a safety feature: "While partial driving automation may be convenient, we don’t know if it improves safety." Followed by a lot of detail about the issues, with citations.

(7) A 2023 study by Lending Tree showed that Tesla was the absolute worst at crashes per 1000 drivers. There are confounders to be sure, but no reason to believe this does not reflect a higher crash rate for Teslas than other vehicles even on a level playing field: https://www.lendingtree.com/insurance/brand-incidents-study/

(8) In December 2023, more than two million Teslas were recalled due to safety issues with autopilot (NHTSA Recall 23V-838). The recall document specifically noted a need for improved driver monitoring and enforcement of operation only on intended roads (for practical purposes, only limited access freeways, with no cross-traffic). The fact that a Part 573 Safety Recall Report was issued means by definition the vehicles had been operating with a safety defect for many years (the first date in the chronology is August 13, 2021, at which time there had been eleven incidents of concern). Initial follow-up investigations by the press indicate the problems were not substantively resolved. (Note that per NHTSA terminology, a "recall" is the administrative process of documenting a safety defect and not the actual fix. The over-the-air-update is the "remedy".  OTA updates do not in any way make such a remedy not a "recall" even if people find the terminology less than obvious.)

(updated 1/1/2024)



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