There is hereby established, within and as a part of the department of revenue, a division of vehicles, the head of which shall be the director of vehicles. Under the supervision of the secretary of revenue, the director of vehicles shall administer the division of vehicles. The secretary of revenue shall appoint the director of vehicles, and the director shall serve at the pleasure of the secretary of revenue. The director of vehicles shall be in the unclassified service and shall receive an annual salary fixed by the secretary of revenue and approved by the governor.