Are you using an Intel HD Graphics GPU? Do you know it's exact model? What OS are you running too? Have you tried if this happens on other Graphics settings too?
I had this problem and I fixed some of the vehicles by putting lighting and mesh quality on high. The best thing you can do is avoid any car or paint design that can support two different colors on the car, like how the Miramar can have a white roof with blue body. Turning up mesh and lighting fixed the Roamer, Grand Marshall, Ibishu Kashira gen 2 (Mod), autobello and a few others, but not the burnside or Miramar.