41 C.F.R. § 102-34.120
Government motor vehicle registration
Government motor vehicles displaying U.S. Government license plates and motor vehicle identification must be registered in the Federal Government Motor Vehicle Registration System. GSA Fleet® may register motor vehicles leased from GSA Fleet®. Motor vehicles that have been exempted from the requirement to display official U.S. Government license plates under this subpart must be registered and inspected in accordance with the laws of the jurisdiction where the motor vehicle is regularly operated.