42 U.S.C. § 7585 — Standards for heavy-duty clean-fuel vehicles (GVWR above 8,500 up to 26,000 lbs.)

(a) Model years after 1997; combined NOx and NMHC standard. For heavy-duty vehicles or engines made in model year 1998 or later, weighing more than 8,500 lbs. and up to 26,000 lbs. GVWR, this part's clean-fuel vehicle standards require that combined nitrogen oxide (NOx) and nonmethane hydrocarbon (NMHC) emissions not exceed 3.15 grams per brake horsepower-hour — equal to a 50% cut from the combined standard that applies to a conventional model year 1994 heavy-duty diesel vehicle or engine under section 7521. No standard applies under this section to heavy-duty vehicles over 26,000 lbs. GVWR. (b) Revised standards that are less stringent. (1) The Administrator may set a less strict standard for these vehicles or engines if the 50% cut in subsection (a) is not technologically possible for clean diesel-fueled vehicles and engines, after weighing durability, cost, lead time, safety, and other relevant factors. To give manufacturers enough lead time, the Administrator had to decide on this technological feasibility before December 31, 1993. (2) Anyone may petition the Administrator at any time to make this determination. The Administrator must act on the petition within 6 months of it being filed. (3) Any less strict standard set this way must still require at least a 30% cut, instead of the 50% cut in paragraph (1).