Automatic braking and better headlights reduce accidents

New data from the Highway Loss Data Institute (HLDI) shows which new safety technologies work and which don't. HLDI examined the difference in accident rates between cars with and without three distinct driver-aid technologies:

• Forward collision mitigation, which uses forward-looking radar and applies the brakes automatically when it detects an imminent collision.


• Lane departure warning, which uses a forward looking camera to detect if the car is drifting out of its lane without the driver activating the turn signal.


• And adaptive headlights, available since at least the 1920s, which steer into a turn at night with the steering wheel.

The study found the biggest benefits from forward collision mitigation systems, which reduced claim frequencies for property damage liability by up to 14 percent on Mercedes-Benz models that offer the system. The system also had smaller benefits in reducing injury and collision claims. Claims for Volvo and Acura models with the system were also lower than those without, although on those cars the system is bundled with other driver aids, so it's impossible to break out which system made the difference. "Driver distraction is such a huge safety issue," says David Champion, senior director of auto testing at Consumer Reports. "Forward collision warning [a similar system without automatic braking], will warn you if you're not paying attention. And collision mitigation will reduce your speed if before you crash," reducing the potential for injury as well as insurance claims, he says.

Surprisingly, the second biggest difference came from adaptive headlights, which reduced property damage liability claims by 10 percent. That number is remarkable, says HLDI, because only 7 percent of crashes occur at night, and an even smaller number occur on curves and involve multiple vehicles (thus triggering property damage liability claims). The Institute says better range or brightness may account for some of the effect rather than simply the fact that the lights swivel. Consumer Reports has been testing headlights since 2003, because "we believe better headlights will improve safety. It's better to see something," says Champion.

Another surprise was that lane departure warning systems seemed to increase rates for all types of claims, though the increases were not statistically significant. Previously, HLDI's sister organization, the Insurance Institute for Highway Safety had suggested that lane departure warnings could reduce fatal accidents from cars running off the road. But in Buick and Mercedes-Benz models with the system, all types of claims went up. They went down for Volvos with the system, but Volvo bundles the technology with forward collision mitigation, which is more likely to account for the difference, HLDI says. Consumer Reports engineers have found that lane departure warning can be a distraction on secondary roads and that many drivers turn it off, thereby negating any potential safety gains.

"While some results indicate the need for further investigation," says David Zuby, chief research officer for IIHS, "it's clear that certain systems, such as those that help drivers avoid collisions with the vehicle in front or better illuminate the road ahead, can play a role in making roads safer for everyone.

—Eric Evarts