This authorization letter allows a representative to transfer ownership of a vehicle on behalf of the lawful owner. Boca Raton, FL 33487.This letter must be typed on COMPANY LETTERHEAD. (Do not change wording). A bill of sale is a legal document that is used to transfer ownership of a car from one person to another in a sale or trade. Certified, return receipt requested letter demanding title to the vehicle to the former owner's last known address. Furthermore, some states will waive certain fees for family transfers.