They get the info on your car and send it to a bunch of used car dealers and get bids from the dealers. They take the best bid and lower by whatever amount they want to make and that is what they offer you.

The auction value is what the dealers are using as a guide line. They look at the book value because they need to know how much banks will finance when they sell the car.

So you could take the same info on your car and text it around to local used car dealers and ask for bids. Maybe you could get more for your car that way. Cut out the middle man.