I've been playing single player again, and have been doing something I should've done from the start.
If you want to see what a car looks like with a certain color, paint it in single player first so you don't waste your money in MP. I lost count on how many times I painted a car with a metallic color and wasted so much money. It's a great money saver.
Thanks R* for giving us a preview option! -_-
^Sig made by Rajeanero