Bro, you just asked one of the most difficult questions.
If you wanna do it outdoors, the location must be cleverly chosen. Look at car mags and you get an idea how you should position the car and how to compose the shot.
To do it indoors, you need a big big studio. I am rather close to some of Singapore's best commercial photographers and have seen them shoot cars. To do it to high standards, you literally need hundreds of flash heads; some of which are fibre optics. Every little reflection and burst on flash on the car counts for something. The entire car is a huge mirror, so getting the shot to be spot-less is already a chore in itself. Imagine how you're gonna position the flashes so they don't appear as reflections.