Improvements for Heavy-Duty Engine and Vehicle Test Procedures

Publication Date: 
Tuesday, June 29, 2021 - 4:00am

This notice of proposed rulemaking includes corrections, clarifications, additional flexibilities, and adjustment factors to improve the Greenhouse gas Emissions Model (GEM) compliance tool for heavy-duty vehicles while more closely matching the outputs produced by the original GEM version 3.0 that was used to establish the CO<INF>2</INF> standards for Model Years 2021 and later in the 2016 Heavy-duty Phase 2 final rule. This document supplements the proposed rule published on May 12, 2020, which included a larger set of proposed revisions to modify and improve GEM. Most of the proposed revisions from that notice of proposed rulemaking are addressed in a final rulemaking published elsewhere in the Final Rules section of this issue of the Federal Register. Given the nature of this proposal, there will be neither significant environmental impacts nor significant economic impacts for any sector.

Environmental Protection Agency