Hi there and welcome to GT Planet!
Your question has been answered here a few times before, but we understand it's quite easy to get overwhelmed by the sheer number of threads and posts here, so hopefully no-one will jump on you for not searching first.
That said, as a good introduction to GTP, have a look through the GT4 FAQs that're stickied at the top of the board.
There's also a thread on this page that's asking for help with Supercar festival, just below yours, so have a look through that as I linked to a post within that thread that should answer your question.
And, as a friendly pointer, try to include a little more information in your thread title. Help! isn't likely to get much response, as people want to know what they're getting into before they visit a thread. Help! isn't very specific, do you want help with your homework? settings? car choice? girlfriend?
To answer your question directly, the Ford GT40 '69 isn't eligible for Supercar, since it's a Race Car.
There's a big difference between a GT40 and a Ford GT. Almost 40 years in fact!
One of the Ford GTs may be eligible, but not the concept version. Make sure if you're trying to enter a Ford GT it's the '05 version that you can win or buy, and not just the '02 concept version.
The Saleen should easily win here too. You shouldn't have too much trouble in that. If you're really struggling, enter and exit before you start the race and try a different AI lineup, watch out for the Mercedes SLR McLaren.
Hope all this helps, and remember, the search function is your friend, the FAQ sections are excellent, the Wiki pages are really helpful and finally....... watch out for
Famine!
