Here are my cars so far. My 240SX is the most heavily modded car I've dealt with so far, since until a little while ago it was the only car I owned in career mode. Until I unlocked the Supra. My Supra is fully modded in terms of what I've unlocked so far, and it's got a new paint scheme, new front bumper, and side skirts. I'll get more stuff on it once I get the money.
The other 3 cars are just arcade mode cars that I created in around 5 minutes. I love the looks on the Evo and the 350Z, but the 206 I modded was my quick attempt to make the most hideous, grotesque car I possibly could using what I have unlocked so far.