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. MORE