Use this car purchase agreement template to customize the financing information for your car along with other required details. A confusing and convoluted document that outlines the selling price, fees, taxes, your trade in, and more.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. This Motor Vehicle Purchase Agreement outlines the details required for buying a vehicle. Complete the Questionnaire and Purchaser's Affidavit. You also may have the seller complete the Seller's Affidavit confirming the purchase price.