IIHS Ratings Expose Driving Automation Flaws

Only one system evaluated earned an acceptable rating for its safeguards designed to prevent misuse and lapses of attention.


The Insurance Institute for Highway Safety (IIHS) released its latest ratings for partial driving automation systems, spotlighting a critical need for enhanced safety measures. The study, which tested 14 systems, found only the Lexus LS's Teammate system to be acceptable. Two were rated marginal, and 11 poor.

“We evaluated partial automation systems from BMW, Ford, General Motors, Genesis, Lexus, Mercedes-Benz, Nissan, Tesla and Volvo,” IIHS President David Harkey said. “Most of them don’t include adequate measures to prevent misuse and keep drivers from losing focus on what’s happening on the road.”

The Teammate system available on the Lexus LS is the only system tested that earned an acceptable rating. The GMC Sierra and Nissan Ariya are both available with partial automation systems that earned marginal ratings. The LS and Ariya each offer an alternative system that earned a poor rating. The Ford Mustang Mach-E, Genesis G90, Mercedes-Benz C-Class sedan, Tesla Model 3 and Volvo S90 also earned poor ratings, in some cases for more than one version of partial automation.

The ratings only apply to the specific models tested even though systems with the same names may be used on multiple vehicles from the same manufacturer.
Vehicles with partial automation are not self-driving — though automakers sometimes use names that imply their systems are. The human driver must still handle many routine driving tasks, monitor how well the automation is performing and remain ready to take over if anything goes wrong. While most partial automation systems have some safeguards in place to help ensure drivers are focused and ready, these initial tests show that they’re not robust enough.

“The shortcomings vary from system to system,” said IIHS Senior Research Scientist Alexandra Mueller, who led the development of the new program. “Many vehicles don’t adequately monitor whether the driver is looking at the road or prepared to take control. Many lack attention reminders that come soon enough and are forceful enough to rouse a driver whose mind is wandering. Many can be used despite occupants being unbelted or when other vital safety features are switched off.”

Partial automation technology -- which includes systems like Tesla’s Autopilot and GM’s Super Cruise as well as feature bundles that provide similar capabilities -- uses cameras, radar or other sensors to “see” the road and other vehicles. It combines adaptive cruise control (ACC), lane centering and various other driver assistance features.

The new IIHS ratings aim to encourage safeguards that can help reduce intentional misuse and prolonged attention lapses as well as to discourage certain design characteristics that increase risk in other ways -- such as systems that can be operated when automatic emergency braking (AEB) is turned off or seat belts are unbuckled.

In some cases, manufacturers are already making changes to their systems through software updates, which may result in adjustments to these ratings. The two Tesla systems evaluated, for example, used software that preceded the most recent recall in December 2023.

IIHS expects improvements to be rapid.

“These results are worrying, considering how quickly vehicles with these partial automation systems are hitting our roadways,” Harkey said. “But there’s a silver lining if you look at the performance of the group as a whole. No single system did well across the board, but in each category at least one system performed well. That means the fixes are readily available and, in some cases, may be accomplished with nothing more than a simple software update.”

For more information on the ratings and the methodology behind them, visit iihs.org.

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