By signing this contract, I choose to purchase the motor vehicle on credit according to the terms of this contract. A Texas motor vehicle bill of sale is a legal document used to demonstrate that a motor vehicle has been sold.Late Registration Penalty. Affidavit of Motor Vehicle Gift Transfer. Includes every type of motorized vehicle used for commercial purposes, such as transportation of goods, wares, and merchandise (NJSA -20). A publication to assist county Tax Assessor-Collectors with collection, remittance and regulations for Texas Motor Vehicle Sales and Use Tax.