I used a few coats of Glossifier over top because I wasn't looking for the matte finish, but I could see it looking nice on a large scale. The only place I had issues, and I imagine you would on a full car coating too, was with the rubber weather stripping around the windshield. The weather stripping is pretty tight up against the painted surfaces / the windshield trim, so getting the plasti-dip to 'break' along that seam was real difficult. I ended up running a razor blade along the seam to cut it, but I imagine that'd be quite the headache on a full-car dip.
-Kevin