Am I understanding you correctly? You glued your vinyl to a piece of 1/4" sew foam with both pieces flat on your work surface and then glued that assembly to the curved aluminum walls of the car? If that's what you did, the vinyl, being the stiffer of the two, being on the outside, and also not being able to conform to the curve exactly like the foam does will cause wrinkles at the curve.
If you glued the foam to the car and then glued the vinyl over the foam, it would work out a lot better for you. It would also be easier if you used stiffer closed cell foam. In either case, you need to do each operation in the car, not on a flat work surface. Your straight piece could be done that way, but not the curved area. Another way to do it would be to make a curved panel to fit the car, glue the foam on the panel, and then glue the vinyl over that. In any case, doing it one layer at a time will stop the wrinkles.
These pictures will show you what happened. I glued a piece of vinyl to a piece of 4 1/2" thick foam flat on my work table. (1st picture) If I curve that assembly so the curve of the foam is in back, (3rd picture) it works fine, actually smoothing out the vinyl even more. When I curve the assembly so that the curve is the other way,(2nd picture) you can see what happens. The thicker the foam, the more pronounced the wrinkles will be. But, when I curve the foam first, and then glue the vinyl on, (4th picture) the vinyl can be smoothed out. Good luck.
No one lives forever, the trick is creating something that will.
Last edited by DanTwoLakes; 01-10-2010 at 08:45 AM.