Actually, there are codes to change cars' colors on the PS2. You have to have a gameshark to do it. It doesn't work on all cars though, like the Tank, the Diablo Stallion, and a few others.
It's the Yardies car (the one with the cool hydraulics), from Staunton Island (don't those guys become a pain in the arse after you finish the Yardie mission!?!). It's normall red.