Prostreet's car's don't look as real as the one's on Most Wanted. If you pay close enough attention to the Prostreet cars you'll see some very disturbing flaws. Sloppy,sloppy,sloppy game.
PCs without the latest GPU > any next-gen console
So yeah, the reason why they don't look real is because of your own computer, which constantly needs to be updated in order to keep up with the consoles. The consoles on the other hand just need a few online patches here and there and it's back on the front line again.
Just... thought I'd throw my two cents in there for some reason. :\