By surfaces I suppose you mean material slots:

I've Included numbers, 1 to 5 would be the items and order to click to get from example 0 to example 6, hope that makes sense.
Edit: Ah, missed the part about the car wheels, so you don't mean material surfaces. Unless they are a separate object parented to the car you'd have to rig the wheels up with bones.
Chances are you can't access your meshes individually since you didn't load/open the object as a new inherited scene.