I believe that sor cars are used by dealers generally to push cars that they have already paid for - after all from a dealer point of view it's free floor candy. This is certainly true in the music instrument world. However, I have known three separate people who have sent their cars to Brands Hatch Motors and been treated very fairly. The cars have sold quickly and for a very reasonable charge. They seem most honourable.
Obviously I've no connection with them; I've not even bought a car from them.
nick