The required documents to sell a car vary by state, but may include a bill of sale, certificate of title, release of lien and odometer statement, according to DMV.org. It is necessary to have signatures from both the buyer and the seller.
A bill of sale serves as a record of the transaction and includes vehicle information, sale date, price and the names and addresses of the buyer and seller, notes DMV.org. A title verifies a car's owner, and transferring it makes a change of vehicle ownership official. A release of lien, or lien waiver, signifies the satisfaction of the terms of a car loan. Odometer statements record a car's mileage on the date of sale.