AMOUNT OF GRANT.

(a) The commission shall develop a grant schedule that:

(1) assigns a standardized grant in an amount up to 90 percent of the incremental cost of a natural gas vehicle purchase, lease, other commercial finance, or repowering;

(2) is based on:

(A) the certified emission level of nitrogen oxides, or other pollutants as determined by the commission, of the engine powering the natural gas vehicle; and

(B) the usage of the natural gas vehicle; and

(3) may take into account the overall emissions reduction achieved by the natural gas vehicle.

(b) Not less than 60 percent of the total amount of grants awarded under this chapter for the purchase and repowering of motor vehicles must be awarded to motor vehicles with a gross vehicle weight rating of at least 33,001 pounds. The minimum grant requirement under this subsection does not apply if the commission does not receive enough grant applications to satisfy the requirement for motor vehicles described by this subsection that are eligible to receive a grant under this chapter.

(c) A person may not receive a grant under this chapter that, when combined with any other grant, tax credit, or other governmental incentive, exceeds the incremental cost of the vehicle or vehicle repower for which the grant is awarded. A person shall return to the commission the amount of a grant awarded under this chapter that, when combined with any other grant, tax credit, or other governmental incentive, exceeds the incremental cost of the vehicle or vehicle repower for which the grant is awarded.

(d) The commission shall reduce the amount of a grant awarded under this chapter as necessary to keep the combined incentive total at or below the incremental cost of the vehicle for which the grant is awarded if the grant recipient is eligible to receive an automatic incentive at or before the time a grant is awarded under this chapter.