I think you will find you have no right what so ever to sell the vehicle. There have been a couple of cases where clampers have sold cars on that they impounded and got royally shafted for it as did the people buying the cars. Clampers got shafted twice in the end, first for selling a vehicle they were not entitled to do so then again by the people who purchased the car and lost it when the court returned it to the original owner