You win a Jaguar XJ13 (20,000,000 a pop) for one of the endurance races. Other than that, plenty of people are willing to trade them for something you can probably afford.
I see a lot of people complaining about money. I don't see the problem. I've only had to buy around 5 cars so far and I've got over 650k in the bank. If you go through the game and try to gold everything it will give you almost everything you need. Sure I don't have every car I want but I can do that later. 9 more gold licenses to get and then I'll work on all the special events I can't do yet. Maybe I'm wrong but I don't see what the big deal is.
The only problem that I see is that these $20M cars of yesteryear are horribly overvalued. I can buy a 2010 Peugeot LeMans car for only $4M or an Audi R10 for a little over that. No real world collector would ever pay $20M for a 330P4, considering it lost to the Ford MK-IV in '67
