You can get free cars by creating a new account on your PS3, signing up for the PS Newtork, and setting your Birthday to the same year a car model was made. For example, if you want the Mercedez Benz Sauber c9 '89 then set the year that you were born to 1989. After creating the account continue on GT mode and you will receive a coupon corresponding to the year of your birthday. You can give the free car as a gift to your real account. Repeat as desired.