The Biden administration is imposing limits on automobile greenhouse gas emissions that were toughened after environmentalists blasted its earlier proposal as too weak.
The standards, which govern the release of carbon dioxide from the tailpipes of cars and light trucks, roughly translate into fleet-wide fuel economy values of 55 miles (89 kilometers) per gallon in model year 2026. They replace mandates weakened by former President Donald Trump and will force automakers to pare 22.6 percent more carbon dioxide emissions from their fleets over the requirements they are replacing.
“We are setting robust and rigorous standards that will aggressively reduce the pollution that is harming people and our planet — and save families money at the same time,” EPA Administrator Michael S. Regan said in an e-mailed statement.
The move takes aim at a major source of carbon dioxide emissions and will help President Joe Biden fulfill his Paris Agreement pledge to at least halve US greenhouse gas releases by the end of the decade. The transportation sector is the single-largest source of greenhouse gas emissions in the US; passenger cars and trucks alone contribute 17 percent of the national total.
The final standards also are expected to encourage more electric vehicle sales, hastening an industry shift that is already underway, with nearly all major automakers having promised to transition their fleets to zero-emission models.
Responding to pressure from environmentalists and public health advocates, the Environmental Protection Agency strengthened the mandates so they are tougher than an initial plan outlined in August and are broadly aligned with requirements the Obama administration charted in 2012.
The EPA’s August proposal would have capped carbon dioxide emissions fleet-wide at 171 grams per mile for model year 2026, potentially translating to a fuel economy value of as much as 38 mpg in real-world conditions. But the EPA tightened the final requirements so fleet-wide emissions are limited to 161 grams of carbon dioxide per mile in model year 2026, potentially translating to 40 mpg. By contrast, the Trump-era targets that are being replaced would have capped tailpipe emissions of carbon dioxide at 208 grams per mile — potentially 32 mpg.
Under the EPA’s projections, the standards are expected help put more electric vehicles on the road — pushing sales of EVs and plug-in hybrids to about 17 percent in model year 2026 from an expected 7 percent in model year 2023.
The mandates, governing passenger cars, SUVs, and light trucks from model years 2023 through 2026, represent the toughest-ever standards of the kind. Still, the administration did not bow to the demands of environmentalists to tighten a suite of proposed credits and incentives that give automakers more flexibility to fulfill the requirements.
Although environmentalists and administration officials had warned those provisions risked undercutting actual, real-world emissions reductions, automakers stressed the flexibilities are vital to meeting the new standards. Without them, the industry wouldn’t have been able to independently satisfy model year 2020 requirements, according to a recent EPA analysis.
In the final rule, the EPA said it would continue effectively overcounting the sales of electric vehicles and rewarding automakers with extra credit for technologies that make cars more fuel efficient but don’t necessarily show up in tailpipe readings.
“Automakers are in a strong position to meet these final standards,” the EPA said. Still, “the program includes averaging, credit banking, and trading provisions to aid the industry in meeting standards through a multiyear planning process.”
Those flexibilities could be critical in the out years, as annual emissions improvements get tougher. For model year 2023, the EPA is requiring a combined fleet-wide average of 202 grams of carbon dioxide per mile — a 9.8 percent increase in stringency over the relaxed Trump-era standards for model year 2022. In model year 2024, requirements would tighten an additional 5.1 percent, followed by another 6.6 percent in model year 2025 and 10.3 percent in model year 2026.
The updated standards set the stage for another tranche of auto standards governing multiple pollutants for model year 2027 and beyond. The EPA is already working to develop that next era of requirements, which it said will govern light- and medium-duty vehicles through at least model year 2030.