N.J. Stat. § 52:31-13: Vehicles required to be marked

Any automobile or other vehicle purchased with funds appropriated by the state for the use of any officer, department or institution of the state, shall be plainly marked or lettered, "state of New Jersey, for official use," together with the title of the officer, or abbreviated name of the department or institution for the use of which the automobile or other vehicle is purchased, which marking or lettering shall be in letters at least one inch in height and conspicuously placed on each side of the automobile or vehicle.