You know how to get one right? Get a multiple of 30 cars in your garage and you'll get a rare paint(probably matte), quit game BEFORE you click ok and go back to the game, if its not chrome repeat.
I have a chrome paint chip just sitting there. I'm still wondering what car I should use it on. If I use it on a supercar, it'll look tacky and lame, if I use it on a 'worse' car, I'l feel like I wasted it.