You have to select one of them and act like you're going to use it, then it asks if you want to pay to unlock level x paints. Once you pay, they all get unlocked (as in switch colors all you want for free), so definately do it. Also, level 2 gives you metalics (click left or right by "gloss paint"), and level 3 gives you perlescant (think chemeleon). I made a pic of the various cars and styles I've had in underground mode and the cars I use for quick race, but I didn't have my CD-RW, so I'll probably post it tomorrow.