Study illuminates big performance gap for car headlights

The difference between the top- and bottom-rated models for a driver’s ability to see down a dark road was substantial, according to the study released Wednesday by the Insurance Institute for Highway Safety, an industry-funded organization that evaluates automotive safety.

The LED headlights in the top trim level Toyota Prius V — the only one of 31 models tested to get the “good” rating — were able to illuminate a straight roadway sufficiently to see a pedestrian, bicyclist or obstacle up to 387 feet ahead.

The reason for the big performance gap is that there’s a lot more to how well headlights help drivers see than merely the brightness of the bulb or even what type of bulb is used, said David Zuby, the institute’s executive vice president and chief researcher.

The halogen headlights in the economically priced base model 4-door Honda Accord, for example, earned an acceptable rating while halogen and LED headlights in two pricier Mercedes-Benz models were rated poor.