Why Are Vehicles Fitted With Rear Fog Lights AUDI A4 B8 Saloon (8K2) (11.2007 - 12.2015)

Rear fog lights on your Audi A4 2015 (and other vehicles) are actually superhero helpers for your safety when the weather decides to throw a tantrum—like fog, heavy rain, or snow that can turn visibility into a major no-show.

Their whole purpose? To shine a bright, concentrated red beam that pierces through thick fog or downpour so drivers behind you can actually see your car’s position on the road. Regular tail lights just don’t cut it in those dense weather conditions because they’re too dim to make you stand out, leading to a dangerous “Where’s that car?” guessing game. Rear fog lights are often about the brightness of your brake lights, but you activate them manually only during poor visibility, not just for show or night cruising.

Now, here’s the catch and why some drivers grumble: if used in clear weather, rear fog lights are so bright they can dazzle or temporarily blind the poor souls tailing you—kinda like flashing a lighthouse in their eyeballs. So, they’re like the “emergency flare” of car lights, meant only for serious foggy situations when visibility drops below about 100 meters. Also, most cars have just one rear fog light on the driver’s side to avoid confusion with brake lights; some newer models might have two but only one should be used at a time.

In short: Rear fog lights are lifesavers in thick fog or heavy precipitation, telling everyone behind “Hey, I’m here, no hitting me!” But turn them off as soon as the skies clear, or risk causing a strobe party for drivers behind you. Keep ‘em for foggy emergencies, and your Audi A4 will stay both visible and considerate!