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US EPA finalizes revised GHG emission standards for MY 2023-2026 light-duty vehicles

20 December 2021

The US Environmental Protection Agency (EPA) released the final rule setting GHG emission standards for model years (MY) 2021-2026 passenger cars and light trucks.

The rule is a second revision of the standards for MY 2017-2025 vehicles that were first adopted in 2012. Last year, under Trump administration, the EPA issued the SAFE rule that relaxed the 2012 standards. Now, in a change of direction under Biden administration, the EPA tightened the standards beyond the levels that were envisioned in the original 2012 regulation.

The final rule significantly accelerates the rate of stringency increases to between 5 and 10% each year from 2023 through 2026. Under the previous standards (the SAFE rule), stringency increased at a rate of roughly 1.5% per year. The new standards are expected to result in average fuel economy label values of 40 mpg, while the SAFE rule standards they replace would achieve 32 mpg in MY 2026.

The standards finalized for MY 2025 and 2026 are the most stringent option considered in the proposed rule.

Projected EPA fleet average CO2 emission levels for different versions of the regulation*
RegulationEPA projected fleet-wide CO2 emission standardsEPA CO2 standards expressed as MPG equivalent†EPA estimated real world label value‡
MY 2026 Standard Projections: Final Rule161 g/mi55 mpg40 mpg
MY 2026 Standard Projections: Proposal173 g/mi52 mpg38 mpg
MY 2026 Standards: 2020 Final Rule (SAFE)208 g/mi43 mpg32 mpg
MY 2025 Standards: 2012 Final Rule180 g/mi50 mpg36 mpg
* All values calculated using the final rule updated fleet mix of 47% cars and 53% trucks in MY 2026.
† MPG equivalent is the MPG assuming the GHG standards are met exclusively by reducing tailpipe CO2.
‡ This is a value that would be comparable to what a consumer would see on a fuel economy label and reflects real-world impacts on GHG emissions and fuel economy that are not captured by the compliance tests, including high speed driving, air conditioning usage, and cold temperatures.

As with EPA’s previous light-duty GHG programs, the standards are expressed as “footprint based curves” for both passenger cars and trucks. Under this approach, each manufacturer has a unique standard for the passenger car and truck categories, for each model year, based on the sales-weighted footprint-based CO2 targets of the vehicles produced in each model year.

The adopted final rule includes some flexibilities for vehicle manufacturers:

The EPA also announced it plans to initiate a future rulemaking to establish multi-pollutant emission standards for MY 2027 and beyond. Consistent with the direction of Executive Order 14037, “Strengthening American Leadership in Clean Cars and Trucks,” this subsequent rulemaking will set standards through at least MY 2030 and will apply to light-duty vehicles and medium-duty (Class 2b and 3) vehicles.

Source: US EPA