There's a load of stunning fictional cars made by Axel that's available on GP4DB. There must be about 60 odd cars to choose from. You're welcome to have my fictional car and graphics, etc. lol. But Axel's are outstanding.
Check out GP4DB, that's my recommendation if you're after a good fictional team! I was going to make a fictional Championship using all of his fictional cars but decided against it in the end in favour of real life teams.