On my way to work today, I had a warning light go off in my Audi A3 that I had never noticed before. Apparently my daytime running right side light had gone out. The funny thing is, I didn’t even realize I had daytime running lights. I also noticed that I have fog lights, but in my ten years of driving, I don’t think I’ve ever used them. So being the curious type, I decided to do some research to see if they really are worth using.
Supposedly, ordinary headlights do not penetrate fog very well. According to my research, regular headlights put out a high intensity beam that reflects a vast majority of the light back at the driver. This is what makes it “hard to see” in the fog—it’s too much light. I don’t know about you, but I’ve never noticed that.
Fog lights use a lower intensity halogen bulb to provide a flat beam of light. This is a big reason why the lights are mounted closer to the bottom of your vehicle. Since fog is just water vapor forming a cloud-like substance, it makes sense that you would want a light closer to the ground so it won’t reflect directly off the cloud of fog.
So apparently there is a purpose for this feature, but from my experience I’ve never needed to use them. Do you use your fog lights? Do they make a difference?