If you've read How Buying a Car Works, you know the car-sales lingo and the ins and outs of negotiating with a seasoned car salesman. Let's say you've battled for the best deal and finally agreed to a price you can live with -- time to breathe a sigh of relief? Not exactly. Did you know that if you finance a new car through the dealership, the finance person is working on commission? That means that the financing deal you get is still up in the air, although they'll never tell you that. Those things that get added on in the final stages of the deal (extended warranties, undercoating, alarm systems, etc.) are often what the dealership makes the most money on. It's the finance-office person's job to upsell you on those items AFTER you've agreed to a price for the car with the salesman.

In this article, we'll cover the choices you have for financing, what determines the interest rate you get, and how to determine if you're really getting the best deal, as well as some scams to watch out for. We'll even give you a cheat sheet to take with you when car shopping to help you figure out things like whether taking the rebate or getting the 0% interest deal is best.