The travel provisions of the General Appropriations Act may establish different aircraft mileage rates:
(1) for travel in:
(A) a single-engine aircraft;
(B) a twin-engine aircraft; and
(C) a turbine-powered aircraft; and
(2) for travel by:
(A) a state employee;
(B) a key official;
(C) a member of a board; and
(D) a member of the legislature.