I favored the SUV for driving....until I got my car maxed out and since it had machine guns I used that more.
But, to get my car max's, I did few races, few stunts. i think if you use the same car too much, you don't get so many points for doing the same stuff over and over again...ie, running over bad guys. Because at the last of it, i didn't seem to be getting many points for running people over with the suv. So for kicks I took the semi. I never used the semi much at all, but all of a sudden Iwas getting crazy points for running people over with it and that is how I got my last star for driving.