Signature of Seller. Bill of Sale to a Motor Vehicle. MV-028.Pdf, Map for TxDMV and Harris County Tax Office Main Location. MV-050. Clearly print or type all information, except signatures. Next, provide the vehicle details, including make, model, and VIN. We will be addressing how to fill out a bill of sale form for the sale of a car so let's get started with this guide to filling out a bill of sale form. Learn about bill of sale laws and requirements for the state of Texas. Get templates for buying and selling high-value items like cars, boats, and firearms.