After filling out the bill of sale, the buyer did not pay, so as a seller, do I still have the ownership of the car? A bill of sale for a car outlines the terms of the transaction and provides proof that a transfer of ownership took place.Whenever you purchase or sell a vehicle privately in New York, you must complete a bill of sale. This is part of the official transfer of ownership. A bill of sale refers to a legal record in the form of a written document that highlights the details of a specific transaction. The proof of sale for a vehicle from a dealer is the Retail Certificate of Sale (MV-50) ("Dealer's Bill of Sale"). (iSeeCars) A vehicle bill of sale is an important legal document when a used car's ownership transfers between two people. These are the terms and conditions of sale (the "Terms") for products and related materials (collectively, the "Products"). A bill of sale is a document that transfers ownership of any property from you to another person (also known as an as is bill of sale).