; and (II) beginning January 1, 2023, shall not exceed 17.5 percent by volume. . II Regulatory harmonization 201. Reid vapor pressure (a) Reid vapor pressure limitation Section 211(h) of the Clean Air Act ( 42 U.S.C. 7545(h) ) is amended— (1) in paragraph (4)— (A) in the matter preceding subparagraph (A), by inserting or more after 10 percent ; and (B) in subparagraph (C), by striking additional alcohol or ; and (2) in paragraph (5)(A), by inserting or more after 10 percent . (b) Existing waivers Section 211(f)(4) of the Clean Air Act ( 42 U.S.C. 7545(f)(4) ) is amended— (1) by striking The Administrator, upon and inserting (A) The Administrator, upon ; and (2) by adding at the end the following: (B) A fuel or fuel additive with respect to which a waiver has been granted in accordance with subparagraph (A) prior to January 1, 2019, and that meets all of the conditions of that waiver, other than the waiver’s limits for Reid vapor pressure, may be introduced into commerce if the fuel or fuel additive meets all other applicable Reid vapor pressure requirements. . 202. Fuel economy adjustment For purposes of fuel economy testing and calculation procedures under section 32904(c) of title 49, United States Code, the fuel economy of motor vehicles using a certification test fuel allowed under section 101 of this Act shall be determined on an energy-equivalent basis, calculated by multiplying fuel economy (as measured under such section 32904(c) without regard to this section) by the ratio of— (1) 114,086 British thermal units per gallon