don't see why it wouldn't be possible.
Might be in the componentpeds image file, but I don't know. Even then, you'd have to export and check a BUNCH of files to find the right texture to mess with.
I just hope R* doesn't start seeing editing of the mesh and text files as a threat and block modified imgs on multiplayer. I like custom cars, but I don't wanna have to swap out files because they're afraid of brightskin mods on multi.