(a) The department is created as an agency of this state.
(b) In addition to the other duties required of the Texas Department of Motor Vehicles, the department shall administer and enforce:
(1) Subtitle A;
(2) Chapters 621, 622, 623, 642, 643, 645, 646, and 648; and
(3) Chapters 2301 and 2302, Occupations Code.