It really depends on what you trade it in on. I was in the car business for years, my old man still has a car lot to this day.

If the dealer has a good amount of cushion he can "show" you more on your car. If not, he's going to try and get the cushion back on your trade.

If your ride has problems or any engine/brake/warning lights on, he's really going to hit you with a low offer, especially on one of our E53's..

The very best thing to do is (1) Sell it yourself. You will probably get close to 30% more. (2) Be prepared to walk away from whatever you are looking to buy. Act super interested, but walk. Usually the dealer will call you back a bit later to try and make a deal. (3) Above all, educate yourself about both vehicles values in YOUR area.