AMD with latest Crimson drivers. Doesn't seem to matter what R3E's visual settings are. Also the Audi's rear lights and trees on the mountain....
This has been brought up before, it's probably because of a phenomenon called z-fighting. Often most pronounced on large tracks. Look up z-fighting on wikipedia, they do a better job explaining it than me. And most likely unsolvable with the current graphics engine.
My experience is also that this is highly hardware- and driver dependent. Not all configurations exhibit this problem as bad as yours seems to do.