Even if you find the code you wont be able to use it, is will say the code have already been used. what you can do tho is to create a 2'nd account on your ps3, with the acconut where you first entered the code on. Go to ps store and download them again, you wont need the code, they'll be there anyway. as long as you dont delete that account, your 2'nd account will get the cars aswell.