If you are looking for a new car, you may be considering a part-exchange. When you part-ex your car at a dealership, the dealer calculates the amount of money he will make on your old car and your new car combined. Dealers may offer you what seems to be a very good part-ex price, but that will probably be to persuade you to buy an over-priced new car! Without doubt, the best way to negotiate at any dealership is to have cash in your hand and be ready to bargain hard.