A car is the second largest purchase most households make and the only one negotiated across four separate transactions at once, which is exactly why it goes wrong. This article separates the four — the price, the trade, the financing, and the back end — and shows how blending them lets a buyer win one and lose three. It explains dealer reserve, the markup on the interest rate, and why the finance office is the most profitable room in the building. It covers the add-on products sold there, which ones are worth buying, and which are pure margin. It explains yo-yo financing and the spot delivery that makes it possible. It covers the Used Car Rule buyers guide, what "as is" does and does not accomplish, the implied warranties that survive it, and the federal warranty act's disclosure rules. It covers odometer and title fraud, the recall system, and the deficiency balance after repossession, which is miscalculated more often than not. A fictional purchase runs throughout.