Why would you give your car up before it was paid in full. By no means is this an exaggeration, I wouldn't give anything to ANYONE (including family members) until it is paid in full. What if the motor blows? Anything can happen and your not protected until your paid in full. Did you even sign a payment agreement with the "buyer"? If you are going to sell something on payment sell houses, at least they can't be driven away.