If you have some one else you can play ad-hoc with, you can test drive it by going to Shuffle Race and changing the PTS setting to 999. From what I have played, you always get a formula car.
I have come across both the Polyphony F1 and the Ferrari F12007, and you need 13,000,000 Cr. to get them both. I am saving up to buy both of them and i will run some tests on them and see if polyphony has something up their sleeves!!!