Bear in mind that a few friends of mine (and me as well) have won the Pro FF Cup by over a lap from the AI in a tuned Mini Cooper 1.3i (178hp). So really, any car you pick will do.
Yeah, there's been plenty of threads going around, I'd recommend a search, or even just looking at the threads on the first page.
Also, welcome to GTPlanet.
i thought liek a week ago this was asked...i know a lot of people think they need help to finish games... but i dunno if hte pro ff really warrants this much discussion... i mean i didnt win it the first time i played... wasnt expecting to have to tune my car too much... but ehh... you dont need to win it right away... just practice...