Circular polarizer for sure. Be sure you can fit one on your camera, then just pick the correct diameter and you are set.
before going to the track, practice at home to see how the effect changes while rotating it
BTW, it's very hard to completely remove glares from a moving car: if parked, you can slowly rotate your filter untill you find the correct position. But when it moves, the angle with wich the light hits the surface constantly change, and the perfect result would be tricky. Still worth the money hands down!