Technically they're very good shots.
Though take a look around and see what other guys are doing - it all looks exactly the same as yours. Try for something different, look for the best angles on the car itself and make that the focal point. The GTI shot is good because the background is more neutral and offers a nice geometric contrast to the soft reflections. My only suggestion would be to remove the chotchke from the mirror.
The Audi shots are nice, again technically very clean and not over processed looking - but the whole "shiny, bagged car in a derelict setting" series has been beaten to death. Look for something new - how does the car get driven? Do they carve back roads? Maybe shoot in in a garage or even a public park. Something that doesn't give off so much visual noise as the abandoned building.
It looks like you understand light and how to operate a camera, not just overcompensating with photoshop, which is nice to see!
Not trying to be a nut buster, but just offering up my (somewhat) educated opinion and trying to be constructive!