As both partial driving automation and highly automated vehicles become more common, we lack commonsense rules to guide their use and collect safety data. So says David Kidd, the Insurance Institute for Highway Safety (IIHS) senior research scientist.

According to research from the IIHS, crash records and insurance data offer little evidence that partial automation systems are preventing collisions.

“Everything we’re seeing tells us that partial automation is a convenience feature like power windows or heated seats rather than a safety technology,” IIHS President David Harkey maintains.

The clearest evidence so far comes from studies of BMW and Nissan vehicles that have been on the road for a number of years. The Highway Loss Data Institute (HLDI) studied these vehicles in 2021. Now a new study of the same vehicles from IIHS confirms that partial automation in these vehicles doesn’t confer additional safety benefits beyond those of crash avoidance features such as front automatic emergency braking (AEB).

More than half the new models for sale in 2023 were available with partial automation systems as an optional or standard feature. Relying on cameras and other sensors, these systems can keep your car moving down the road in the center of the lane, navigating curves, slowing down to avoid other vehicles and then accelerating again when the way is clear.

But vehicles equipped with these systems are far from self-driving. They can’t manage many routine roadway features and traffic situations, so drivers must pay close attention to what’s happening on the road and be ready to take over at any time. That’s a big challenge because the technology can encourage a false sense of security and induce boredom, causing drivers to tune out.

There’s a key difference between partial automation systems and the crash avoidance features. Crash avoidance features like AEB, blind spot warning, and lane departure prevention come into play only when a potential danger arises — slamming on the brakes to avoid rear-ending another vehicle, for example. Because such features are not noticeable under normal circumstances, most drivers who use them leave these features switched on all the time.

In contrast, a partial automation system works constantly to keep the vehicle in the desired position on the road. Intended for use on highways and other limited-access roads, such systems must be switched on whenever the driver wants to use them. Most drivers do so only occasionally.

Broadly speaking, the studies have all shown that features that warn or intervene in an emergency reduce the frequency of insurance claims. Partial automation could also theoretically help prevent crashes. So far, there’s little evidence that’s happening.