Help with Test Drive Unlimited 2? Easy money and selling of cars?

So I have beaten the game and have bought plenty of cars and houses, but I still would like to get more. I spent most of my money and went to replay the $1,000,000 race, but it didn't give me any money so it was a waste of my time. I am wondering if there is any way you can make easy money without driving around in circles to get FRIM. I don't understand why you can't sell any of the cars that are given to you either. So answering that would help me also. I know about the casino, but that's a gamble and I don't want to waste that kind of money. Thanks