Section was formerly classified to section 1857f–6f of this title.

A prior section 213 of act July 14, 1955, was renumbered section 214 by Pub. L. 93–319 and renumbered section 216 by Pub. L. 95–95, and is classified to section 7550 of this title.

1990—Pub. L. 101–549 amended section generally, substituting present provisions for provisions requiring Administrator and Secretary of Transportation to conduct study on fuel economy improvement for new motor vehicles manufactured during and after model year 1980.

Pub. L. 108–199, div. G, title IV, § 428(b), Jan. 23, 2004, 118 Stat. 418, provided that: “Not later than December 1, 2004, the Administrator of the Environmental Protection Agency shall propose regulations under the Clean Air Act [42 U.S.C. 7401 et seq.] that shall contain standards to reduce emissions from new nonroad spark-ignition engines smaller than 50 horsepower. Not later than December 31, 2005, the Administrator shall publish in the Federal Register final regulations containing such standards.”