IIHS Study Says Partial Automation May Not Prevent Crashes

The Insurance Institute for Highway Safety — the people who crash cars to determine which ones are safest — and its associated research organization, the Highway Loss Data Institute, have a startling announcement amid the explosion of active-safety tech across the car market: Partial automation does not prevent crashes.

Related: Automatic Emergency Braking to Be Mandated on All New Vehicles by 2029

To contextualize, consider the root technologies of partial automation: adaptive cruise control and lane-centering assist. IIHS and HLDI say that data show these two systems do reduce the number of crashes. To arrive at this conclusion, the two organizations studied crash data on model-year 2017-19 Nissan Rogues with the automaker’s ProPilot Assist system, as well as a number of model-year 2013-17 BMW models with Driving Assistant Plus.

Root Technologies Work

Both are examples of partial-automation systems that use adaptive cruise control and lane-centering assist to keep the vehicle a safe distance from other road users and centered in its lane but do not promise any degree of hands-free operation. The agencies noted, “There’s a key difference between partial automation systems and the crash avoidance features that are usually included with them but also sold separately.”

HLDI data analysts found 8% fewer insurance claims for rear-end accidents for Rogues equipped with forward collision warning and automatic emergency braking than in those without the tech. They observed a similar reduction in BMW and BMW-owned Mini vehicles with those brands’ similar systems. However, they say they found “no additional benefit” in Nissans equipped with ProPilot Assist or BMWs and Minis with Driving Assistant Plus.

Reducing Situational Awareness

IIHS and HLDI note that one potential problem with features like these is that they “can encourage a false sense of security and induce boredom, causing drivers to tune out.” Rather than closely following traffic conditions as they develop and spotting potential troubles before they become urgent, drivers lulled into complacency by such technologies instead must snap to attention and may have only a split second to fully comprehend a complex situation and decide how to react — or just panic and crash.

HLDI acknowledges that the vehicles in its study are between five and 11 years old, and that these technologies are advancing rapidly. “It’s possible,” the Institute allows, “that new partial-automation systems are more effective from a safety perspective.” On the flip side, that these vehicles have been in circulation longer has allowed for a more comprehensive pool of data concerning them to develop.

Jessica Cicchino, IIHS senior vice president for research, said, “With no clear evidence that partial automation is preventing crashes, users and regulators alike should not confuse it for a safety feature.” IIHS President David Harkey concurred, adding, “Everything we’re seeing tells us that partial automation is a convenience feature like power windows or heated seats rather than a safety technology.”

More From Cars.com:

• Which Cars Under $40,000 Have Earned IIHS Top Safety Pick and NHTSA 5-Star Awards?
• What’s the Safest, Most Affordable Car for Teens?
• New IIHS Crash-Prevention Test Shows Gaps in Active Safety for Small SUVs
• More Safety News

Corroborating the Evidence

HLDI’s data comes from insurance companies covering 85% of the privately owned vehicles in the U.S. The institute notes its data doesn’t indicate whether partial-automation systems were active at the time of a crash or the type of road where the crash occurred — so, to bolster its findings, Cicchino analyzed data on crashes for the same BMWs and Nissans from police departments in 17 states from 2013-22. Again, these reports don’t record whether partial-automation systems were active at the time of the collision, but by restricting her study to the types of front-to-rear and lane-departure crashes such technology is intended to prevent, Cicchino was able to draw broad conclusions.

While this approach initially seemed to suggest a benefit to partial automation, it was noted that crash rates were similar on the high-speed roads where such technology is likely to be enabled and the low-speed roads where, as IIHS notes, “the added convenience it provides is minimal at best.”

This, IIHS concludes, suggests some other feature of the vehicles (or their drivers) was a contributing factor. The data showed that the apparent difference in crash rates was most pronounced in the dark, and certain model-year Rogues from the range studied were more likely to be equipped with upgraded headlights when they also had ProPilot Assist. Previous IIHS research has shown a 15% reduction in nighttime crashes for vehicles with headlights that rate acceptable in its four-tiered ranking system compared to those that earn the lowest score of poor.

Cars.com’s Editorial department is your source for automotive news and reviews. In line with Cars.com’s long-standing ethics policy, editors and reviewers don’t accept gifts or free trips from automakers. The Editorial department is independent of Cars.com’s advertising, sales and sponsored content departments.