Find out what documents you will need to provide proof of sale and ownership if you are buying, selling, or gifting a 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. Watch this before you finance your next car (former dealer explains how to read a purchase contract) This form certifies the purchase price and determines the sales tax you must pay when registering the vehicle. 1 If you're financing your purchase ; 3 The actual vehicle purchase agreement ; 4 Buyer's trade in certification ; 5 Warranty disclaimer and documentary fee notice. I left with a signed purchase agreement from the dealership. We've put together this guide to simplify car purchase agreements and help you stay protected when purchasing vehicles or selling them. 1. Enter the buyer's name and contact information.