All motor vehicles owned and operated by the state, except vehicles under the control of the central vehicle management system and the official vehicle for use by the governor, must have displayed on each front door the words NORTH DAKOTA. The words must be in letters four inches [10.16 centimeters] in height. Two and one-half inches [6.35 centimeters] directly below those words there must be printed in letters one and one-half inches [3.81 centimeters] in height the name of the state agency owning or leasing the motor vehicle. The width of the display required by this section must be proportionate to the required height. The color of the lettering must be in clear and sharp contrast to the background. The state auditor shall include in the auditor’s report to the governor and the legislative assembly any instance of noncompliance with this section. The above requirements and the requirements for no smoking signs do not apply to vehicles operated by a state entity that engages in investigatory activities. The central vehicle management system vehicles must display a window decal designed by the director. The state highway patrol and all peace officers of this state shall enforce this section.