Mass. Gen. Laws ch. 30 § 36
The commissioner of administration shall establish and enforce regulations governing the use and marking of motor vehicles owned by the commonwealth. Every office, department, board, commission or institution of the commonwealth shall keep such a record of the use of such vehicle, and shall make such reports in relation thereto, as may be prescribed by such regulations. Every such vehicle shall be plainly and conspicuously marked in such manner and place as shall be prescribed by such regulations. No such vehicle shall be used for providing transportation for state officers and employees between their domiciles and places of employment nor shall any expense be incurred for the garaging of such vehicles except with the prior written approval of the officer having charge of the agency operating such vehicle, and, in the case of a department, office, commission, or institution within any of the executive offices established by chapters six A and seven upon the prior written approval of the secretary having charge of such executive office, and in accordance with such regulations; provided, however, that the commissioner of administration may issue rules and regulations governing the use of such motor vehicles for emergency purposes.
The commissioner of administration is authorized to transfer a motor vehicle from one agency or department to another and may transfer any such vehicles to the executive office of administration and finance to be maintained, serviced, repaired and garaged thereby and assigned to departments or agencies on such basis and for such duration as the commissioner may deem appropriate.
The registrar of motor vehicles shall furnish for each motor vehicle owned by the commonwealth a distinctive number plate bearing such arrangement of letters or number or both, as will distinguish the particular vehicle, and in the discretion of said registrar, as will distinguish the officer, department, board, commission or institution by which the vehicle is operated.
Mass. Gen. Laws ch. 30, § 36