buying used cars
It is money that is given to the dealer from the factory when the car is sold. Every new purchase has a clause in the contract that usually states that the deal is subject to loan approval. If a dealer approaches you about the hot car tell him that you are not interested because it will not be worth the money next year as the new hot car will be out by then. See, they will tell you that you can afford to buy the car at MSRP hoping that you will not then wonder what the actual worth of that car is. So in the end your offer should be calculated like this: Calculating your offer to a dealership is as simple as that.

bluebook used car
Some dealerships will not let you. Since you now know how to calculate your offer and already know what the dealer paid for it, you should get a copy of the paperwork from a friend that recently bought a car, so that you can become familiar with what you will see on your paperwork. The finance manager is counting on you being confused and desperate to get out of there, so assumes you will simply go along with whatever he says.