I was in a local radio show Harley give away a couple years ago with several hundred people. I made it to the round of 16 and was beginning to feel quite confident. My mind started wandering off to " how much can I sell this for,will they give me cash instead, If I ride it straight to a dealer what's the trade in value. Needless to say I came crashing back to the ground when I was eliminated in the next round. Got on the trusty Triumph and rode off with a good chuckle knowing all those Harley guys were getting pissed thinking the guy in the Triumph jacket and cap was about to steal one of their hoglets.
It ain't what most people think. When you win the vehicle is titled in your name that means you pay all applicable state and local taxes on it which on a $30,000 car can be a little coin. Then since it has been titled it is now officially a used car with one recorded owner so the book value has dropped accordingly. Of course since the dealer has to sell the "used" vehicle at book value they ain't going to give the winner book he'll get average trade value at best. In the end the winner is usually irked at the percentage he gets of that fat sticker price, the real winners are the dealership and second owner.