pretty good answer though! and are we talking grand turismo psone or ps2, i assume psone as i recall the first 2 on psone? and if it is psone then theres an emulator for pc, so his answer does actually hold ground after all! lol
Some of the games with common (dare I say, "Open") standards allow you to draw your own car and use it. There are paper model Cinqs available as .jpegs out there, so that might be a good place to start.