I'm Diamond too. I'm shining like the McLaren F1 McLaren'sAngel fantacizes.
Man, Cobragt's rough run of luck continues to burn in hell. Anyhow, not a good idea. What if a car from GT3 won't be in GT4? And keep in mind, you'll have to pay for those cars from GT3, so you can't Gameshark your way to glory, and even then, it's STILL cheating. I'd only want to trade cars if I get some special files from a PS2 disk and use that as an alternative garage. I had a CD which contained extra cars to use in Gran Turismo 3. But here's the thing. I kept my old game and just use the other Memory Card to trade cars with. I didn't race with the other Memory Card because I still wanted to beat the game. Since I had some money, I could use some of the race cars, even the Luop Race Car that has the handling of a Le Mans race car, but very low on horsepower. So anyhow, I'd rather work my ass off and make money and win races.