Check with your local provincial transportation ministry for a template bill of sale for use when selling a car. If you’re considering buying or selling a vehicle, here’s what you need to know about a. For example, an enforceable bill of sale: As the official receipt of a private used car sale, a bill of sale is used to transfer ownership of a used vehicle from the seller to the buyer and is required by most provinces to officially register the car under the new owner's name and license plates. For example, in the case of the purchase of a used vehicle, provincial legislation often requires a bill of sale to register the vehicle to the new owner.