I think what you wish to do is a bit too esoteric for a specific program. Although, there was an article in Street Rodder (?) a year or so ago that allowed you to use templates to do a limited variety of paint scemes.
I suggest Photoshop which I have, but even after taking a class at a local community college, I never mastered the program. The doorknob teaching the class had us buy two expensive books and then proceeded to read them to the class. That guy couldn't sell Vasoline at a Gay Pride Picnic.
It's been a few years since I even used the program to show me and Pam Anderson dating (just kidding) so there might well be better programs out there.