O.K.
As others have said, it is irrelevant if the vehicle is registered in your name and you paid taxes. When the title changes to ANOTHER owner, and he registers the vehicle in his state, HE OWES TAXES IN THE STATE HE RESIDES ON PURCHASE PRICE. Period. Now if you trade a car in, yes, at least in PA, you will only pay tax on the remaining value (Car price - trade price). But to 'Make-believe' you traded a car to reduce the tax MUST BE ILLEGAL. Not sure if the liability would be on the dealership or the purchaser, but SOMEONE is doing SOMETHING illegal. If not, I would trade in 'Make-believe' vehicles 24/7.