You would be liable for paying your portion of the auto repairs as per the agreement even though the car was traded in.  You would be liable for those repairs because if your friend paid for all of the repairs before trading the car in, she is out your unpaid share of the repairs.  If she didn't get the car repaired before trading it in, she got less value for the trade than she would have received if you had paid your share of the repairs.If she had insurance, the insurance company wouldn't pay for the repairs because you were at fault in the accident and she was the registered owner of the vehicle.Since she doesn't have insurance, she could be sued by the registered owner of the truck you hit.  If that happens, she could sue you for the amount of a judgment against her.If the registered owner of the truck had uninsured motorist coverage, the truck owner's insurance company will pay for the repairs to the truck, but the insurance company will then sue your friend for the cost of repairs to the truck.