If your son allows the truck to be repossessed, he will still be obligated to pay any balance left over after the dealership sells the vehicle. The same will hold true if your son files for bankruptcy. This may be a greater amount than what your son will lose by selling the truck on his own. If he is unable to sell the truck on his own and he still needs a vehicle, he can go to the dealership and see what he can get for the truck on a trade for another vehicle. He may lose money in the sale of the truck, but if he is unable to make payments on the truck, he will end up losing a lot more money.