IIHS Warns on Reliability of Driver-Assist Systems

Driver-assist systems that provide automatic steering and braking can be lifesavers, but they also can lead you into a crash, cautions the Insurance Institute for Highway Safety.

IIHS’s advice to drivers: Pay attention, because these safety systems don’t always make the right decisions—and none is capable to driving safely on its own.

In a paper titled Reality Check, the IIHS assesses driver-assist systems from BMW, Mercedes-Benz, Tesla and Volvo at a test track and on public roads.

The institute, which previously rated all the systems “superior,” confirms they can avert crashes and could save thousands of lives per year. But it warns that the technology isn’t 100% reliable and could cause more harm than good.

Hills and curves can confuse an automatic lane-keeping system, for example, causing it to veer toward the shoulder or across the lane line. On the highway, such systems may follow a leading vehicle into an exit lane when your intention is to stay on the main road.

Similarly, automatic braking systems work well when traffic slows down and then speeds up. But the feature may fail to detect or respond to an already-stopped vehicle ahead. On the other hand, such systems may brake unexpectedly when they detect oncoming traffic, a tree’s shadow on the road or a vehicle crossing the roadway far ahead.