I have thought about doing it as well. The closest thing that I have painted is an Iron Man resin model. I would at least suggest that you use model paint that is made to be sprayed up close, not like Krylon. If I would go through with it, I would go to a hobbyist/comic shop. They may have know someone that uses real air brushes to paint figures and models, and the results are way better than anything you can do yourself with spray and an oven. It may cost a bit, but you could have him add discoloration to the exhaust, etc., and do up the car completely.