One problem that comes up for almost all middle-aged cars is foggy headlight covers. Over time, ultraviolet light from the sun and the general weathering effect of wind, rain, and dust from the road combine to degrade the plastic covers that protect most modern vehicle headlights. When that happens, less light can get through and the headlights begin to appear dim.
What happens is that the plastic becomes scuffed by the constant wind and dirt, making the surface less transparent. Then the UV radiation makes the degraded plastic appear cloudy. Old headlight covers may even take on a yellow color in extreme cases. Fortunately, there are several easy ways to eliminate the cloudiness and restore the covers. You just have to polish out the micro-scratches and remove the layer of oxidized and UV-degraded plastic on the surface of the headlight cover. Here's how you do that.