Originally Posted by Verdugo
...generally you don't want to use any filters at night. I've still had success using my circular polarizer, but at the same time, I've noticed it wasn't necessarily needed either.
Yeah, this one really depends on the situation. Some night locations create notorious reflections and glare on the sides of cars and windshields. Sometimes you just can't get away from it (especially at meets where you don't have free reign on car placement), so the CP comes in handy when trying to reduce this:
I tried this shot without the CP, and the car had all sorts of reflections and glare on it, although I did do some touch-up work to reduce the blown out areas on the car from the lights in the parking lot.