# Improvements for Heavy-Duty Engine and Vehicle Test Procedures
> **Rule** · Final rule. · Published 2022-07-28 · Effective 2022-08-29 · 87 FR 45257
## Document
- **Document number:** 2022-16031
- **Category:** air-emissions
- **Federal Register citation:** 87 FR 45257
- **CFR reference:** 40 CFR 1036
- **Publication date:** 2022-07-28
- **Effective date:** 2022-08-29
- **EPA docket:** EPA-HQ-OAR-2019-0307
## Abstract

This final rule 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. Given the nature of this rule, there will be neither significant environmental impacts nor significant economic impacts.

## Source
- [Federal Register document](https://www.federalregister.gov/documents/2022/07/28/2022-16031/improvements-for-heavy-duty-engine-and-vehicle-test-procedures)
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