Tex. Tax Code § 152.090
(a) In this section, "hydrogen-powered motor vehicle" means a vehicle that meets the Phase II standards established by the California Air Resources Board as of September 1, 2007, for an ultra low-emission vehicle II or stricter Phase II emission standards established by that board and:
Added by Acts 2007, 80th Leg., R.S., Ch. 1266 (H.B. 3319), Sec. 10, eff. September 1, 2007.