Find out what documents you will need to provide proof of sale and ownership if you are buying, selling, or gifting a vehicle. This form certifies the purchase price and determines the sales tax you must pay when registering the vehicle.You'll need to sign the car purchase agreement (or dealer bill of sale), the title, an odometer statement, and sometimes a damage disclosure statement. This car purchase agreement template is a standard agreement made completely customizable for your individual needs. A confusing and convoluted document that outlines the selling price, fees, taxes, your trade in, and more. Information you can expect to fill out includes the car's VIN, make, and model, the name and permanent address of each party involved, and the sales amount. Here are six of the most important documents you'll be asked to sign when you're making a deal on a car. We'll also point out which section matters most.