There may be a reason why people have trouble seeing while driving at night, and it's not their eyesight. A new rating of the headlights of more than 30 midsized car models gave only one model a grade of "good."
Of the rest, about a third were rated "acceptable," a third "marginal" and a third "poor." 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. At that distance, the vehicle could be traveling up to 70 mph and still have time to stop.
But halogen headlights in the BMW 3 series, the worst-rated ones, were able to illuminate only 128 feet ahead. At that distance, the vehicle couldn't be traveling at more than 35 mph and still have time to stop, according to the study.
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.
"We found the same light bulb, depending upon what reflector or lens it's paired with and how it's mounted on the vehicle, can give you very different visibility down the road," he said.
It gets more complicated. Consumers can't buy a more expensive model or add an expensive technology package and necessarily expect to get better headlights, the report said. 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.
