In Test Drive Unlimited 2 there is no clear way of selling cars, apart from when your garage space is full or you don't have enough money to buy a car. What i do is if i have got say 3 spaces left in my garage and i want to sell a car, go and buy the Lotus esprit, and/or the Lancia Delta, and/or the Chevrolet Mustang or any other cheap cars and when your garage is full go to buy a car you want then sell the cheap cars you just bought aswell as the car you originally wanted to sell. If you dont have space and you want to sell a car then do it normally. :)