Your scenario is the most common reason why co-signing for the loan to another person is rarely a good idea. Can you take the car because you have a key? No. If you are on the title/registration as a co-owner of the vehicle, then you have equal rights to the vehicle as your (former) friend. Possession of a key is not sufficient.
Can you take him to Small Claims Court? Yes, but.... You are jointly liable for the debt. With co-ownership comes co-equal duties to pay for the car. Therefore the Court might state that unless and until you adjudicate ownership and possession rights (who has paid what), requiring reimbursement between the 2 of you is premature. As you friend notes, this scenario feels like a "Golden Rule" example: he who has the gold (car) gets to make the rules and has the upper hand. You should seriously consider not making further payments until you can secure the automobile or its disposition.
Answered on Apr 25th, 2013 at 3:40 PM