"All in one" type lenses like 18-200 / 70-300, generally suck and reproduce soft images. Your prime lens will eventually become your most valuable lens in your bag if you know how to use it. For automotive photography, in my opinion, IS and VR type crap suck. I tried an 70-200 Nikon VRII and I didnt like it at all and couldnt see a difference in images when fully cropped. Nothing that would be detectable anyways.

Either way id look into a Canon 70-200L glass or maybe even a 130mm Prime if you guys have one. Im sure yall do.