^^^^^ What Scott says is helpful.
To that I would add: PLAY
Take any car, your own is just fine, and just shoot it at different focal lengths, from different distances, in varying settings.
A Polarising filter is a good toy. Play with varying how the reflections on the surface shine can be varied and the impact changed.
Keep two things in mind that commercial shoots favour:
1. Shoot at dawn or dusk to get a glow in the paint work
2. Find a location that has a large natural reflector such as a white wall to give contours in the shadow side.
A mate of mine in the UK shoots cars for brochures — Bentleys, Jaguars, etc. Get some clues from looking at his work: