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. Use this car purchase agreement template to customize the financing information for your car along with other required details. I'm gonna break down all the terms and conditions so you can understand what it means and we're gonna fill that out so you can have a real-life example of it. 1. Enter the names of the Seller and Buyer along with the agreement date. A confusing and convoluted document that outlines the selling price, fees, taxes, your trade in, and more.