Do you mean make one from scratch or just edit the colors and appearance. You can do both in MS Paint (just basic paint that should come on your computer), just remember to save as a gif.
Basically get a good pic of the car (a printout, picture that you own, or even a diecast model) and just get as close to the real thing as you can. And I don't know why you are rolling your eyes, I don't have to say anything you know.
i cant figure out how the heck to do those cool gif car drawings, the only freakin thing i could do is alter or re-do someone elses
OH AND ON THE DRAWING BELOW TOO!!!!! 
