Legal Question in Credit and Debt Law in California

Sue them or repossess the car.

You had no right to transfer the car since it was not yours to transfer. The bank has legal title. You are only a registered owner. You need to recover the car and make payments or recover the car and let the bank repossess it. You can try to sell it if you find someone that will pay off the loan first. You must keep the vehicle insured because you will be liable for any loss of the vehicle and damages/injuries to others in connection with the car. If the people to whom you gave the car will not give it back you need to see a lawyer about how you can get it back by obtaining a court order or if you can just pick it up and bring it home. Check with a lawyer first.