So I bought the game, installed it and it worked. The Problem occurred when I got under the wheels of the 370Z.
Take a Look at the picture, you can see a small black box on the top left. What do you think is it?
It doesn't appear in the menu or during movies, only when driving.

9960

NFSUC was released in pre-alpha stage. You could try updating your drivers. But I am positive its an in-game bug. I doubt its your graphics card because even on my card I'd get some really annoying flickering

Ok I fixed the problem, just had to turn Smoke Off :D

i love how that truck flies...