Semi-autonomous driver assists are a convenience but aren't safer, IIHS study shows

Now that cars with driver-assist technologies have been on the road for several years, it’s possible to gather crash data to see if such features actually help prevent accidents. According to analysis of collision data by the Insurance Institute for Highway Safety, the answer is not really.

The study looked at data collected by the Highway Loss Data Institute of Nissan and BMW vehicles from 2013 to 2022. Both brands have a significant number of vehicles equipped with partial autonomous driving features — ProPilot for Nissan and Driving Assistant Plus for BMW. The IIHS found that the presence of such features like lane departure and lane centering did not result in a statistically significantly reduction in collisions.

Cars equipped with those features tended to also have forward automatic emergency braking. The IIHS classifies AEB as a crash avoidance feature, not  a partial autonomous feature.

By contrast, the study revealed that cars equipped with AEB saw a notable reduction in insurance liability claims, which are claims where other drivers’ property is damaged. For example, 2017-19 Nissan Rogues equipped with forward collision warnings saw an 49% lower rate of rear-ending crashes. If the Rogue was equipped with AEB and ACC as well, the rate dropped by 54%. 

More broadly speaking, Nissans equipped with AEB saw an 8% drop in liability claims, while 2013-17 BMW and Mini vehicles equipped with AEB saw a 13% lower rate. The data didn’t allow for IIHS to isolate BMW and Mini rear-ender crashes.

“With no clear evidence that partial automation is preventing crashes, users and regulators alike should not confuse it for a safety feature,” warned Jessica Cicchino, senior vice president for research at IIHS. In fact, the IIHS cautions that such features could “encourage a false sense of security and induce boredom, causing drivers to tune out.”

As a result, IIHS president David Harkey said that partial autonomous features should be thought of as a convenience like power windows or heated seats, not as safety features.