geez, i feel like such a geek, but not all of the f1 cars are true F1s. I just won the F686 from the Laguna Seca enduro, and if you'll look at the specs, you'll see that it's a turbo-charged V6. FIA rules for F1 engines dictates that the last couple of years models' had to be NA V10's.
there's a lot of styling differences in the chassis' btw the F090-S and the F686. since I haven't seen them all, i don't know how many of them are CART/Indy style, and how many are bona fide F1 cars, but they certainly are in the Formula genre, and kick major butt...