; and (B) the installation of that system occurred after the initial sale of the motor vehicle. (3) No preclusion of orders Nothing in this subsection precludes the Administrator from issuing an order to prohibit the manufacture, sale, distribution, or installation of an aftermarket conversion system if the Administrator has evidence that the installation of the aftermarket conversion system on a motor vehicle degrades emission performance. . (b) Biomass fuels Section 211 of the Clean Air Act ( 42 U.S.C. 7545 ) is amended by adding at the end the following: (w) Biomass fuels Notwithstanding any other provision of this Act, the Administrator may not prohibit or control biomass fuel (as defined in section 203 of the Biomass Energy and Alcohol Fuels Act of 1980 ( 42 U.S.C. 8802 )) under this Act. . 3. Calculation of average fuel economy (a) Definitions Section 32901(a) of title 49, United States Code, is amended— (1) by redesignating paragraphs (7) through (19) as paragraphs (8), (9), (10), (13), (16), (17), (19), (20), (21), (22), (23), (24), and (26), respectively; (2) by inserting after paragraph (6) the following: (7) biodiesel — (A) means liquid fuel derived from biomass that meets— (i) the registration requirements for fuels and fuel additives established by the Environmental Protection Agency under section 211 of the Clean Air Act ( 42 U.S.C. 7545 ); and (ii) the requirements of the American Society of Testing Materials Standard D6751; and (B) does not include any liquid with respect to which a credit may be determined under section 40 of the Internal Revenue Code of 1986. ; (3) by inserting after paragraph (10) (as so redesignated) the following: (11) E85 means a fuel mixture that— (A) contains between 51 and 83 percent ethanol; and (B) meets the specifications of the American Society of Testing Materials Standard D5798. (12) flexible fuel vehicle means a vehicle that has been warranted to operate on gasoline, E85, and M85.