How Consumer Reports tests cars:

Headlights

Have you ever wondered whether your car's headlights are as good as they should be? To answer that question, Consumer Reports evaluates headlight performance on new cars in our test program. After aligning the lights in an indoor lab, we test them outdoors at our track on dark, moonless nights. Our headlight specialists set up a series of black targets at prescribed intervals along almost a thousand feet of level roadway. They then look for low-beam and high-beam performance, evaluating reach, intensity, width, and the evenness of the light pattern. They note glare effects— where stray light can bounce back from mist, rain, or fog. And they determine whether the transition or cutoff of light is so sharp that it reduces the headlight's range as it moves over curves, dips, and uneven roads.