(1) Whenever it becomes necessary for elective or appointive officials or employees of the state to travel away from their designated posts of duty while engaged on official business, and it is found to be more advantageous or economical to the state that travel be by a privately-owned vehicle rather than a common carrier or a state-owned or operated vehicle, a mileage rate established by the director of financial management shall be allowed. The mileage rate established by the director shall not exceed any rate set by the United States treasury department above which the substantiation requirements specified in Treasury Department Regulations section 1.274-5T(a)(1), as now law or hereafter amended, will apply.
(2) The director of financial management may prescribe and regulate the specific mileage rate or other allowance for the use of privately-owned vehicles or common carriers on official business and the conditions under which reimbursement of transportation costs may be allowed. The reimbursement or other payment for transportation expenses of any employee or appointive official of the state shall be based on the method deemed most advantageous or economical to the state.
(3) The mileage rate established by the director of financial management pursuant to this section and any subsequent changes thereto shall be reported to the ways and means committees of the house of representatives and the senate at each regular session of the legislature.
(4) No person designated as a member of a class one through class three or class five board, commission, council, committee, or similar group may receive an allowance for subsistence, lodging, or travel expenses if the allowance cost is funded by the state general fund, unless authorized under RCW 43.03.220
or granted an exception under RCW 43.03.049