The Trump administration has reopened the Obama-era greenhouse gas standards for vehicles manufactured between 2021 to 2025.

U.S. EPA Administrator Scott Pruitt and Transportation Secretary Elaine Chao yesterday signed and published a notice asking for comments on the rules.

President Trump announced he would review the tailpipe standards at the request of automakers in March. The opening of the docket marks one of the first formal steps of the process, which could end in lowered stringency.

The notice also marks a power shift away from EPA, which regulates greenhouse gases coming from cars, toward the National Highway Traffic Safety Administration. That has escalated tensions with California and environmental advocates who are concerned about the climate impacts of motorized vehicles.

“EPA appears to be abandoning efforts to protect Americans and the environment against global warming by handing over clean car rules to much weaker fuel economy regulators at NHTSA,” said California Air Resources Board Chairwoman Mary Nichols in a statement.

In a surprise move previously reported by E&E News, the Trump administration has broadened the review to also reconsider the standard for model year 2021, which is already on the books (Greenwire, Aug. 8). NHTSA first announced it was reconsidering its 2021 standard late last month.

California and a dozen other states have already adopted stringent vehicle rules through 2025. Golden State officials vowed a fierce legal battle if the federal rules change.

By 2025, the Obama-era rules were projected to bring the average real-world fuel economy of cars and trucks to around 36 mpg, or a corporate average fuel economy (CAFE) target of between 50 and 52.6 mpg.

Automakers have said the rules are expensive and difficult to meet as consumers flock to gas-guzzling trucks instead of fuel-efficient or electric cars. EPA has agreed to take more data on consumer preferences into account as it reviews the rules.

A safety regulator takes the helm

The result of the review could hinge on who does the analysis.

The fuel economy program began in 1975 following passage of the Energy Policy and Conservation Act, which was meant to boost the United States' independence from foreign oil. EPA began regulating tailpipe greenhouse gases in 2009 following the Supreme Court decision in Massachusetts v. EPA two years earlier.

Under the Clean Air Act, the agency's standards must be technology-forcing. The Energy Policy and Conservation Act requires NHTSA's standards to be the “maximum feasible.”

“[NHTSA's expanded role] will result to lower standards because of different requirements in their respective laws,” said Margo Oge, the former head of EPA's Office of Transportation and Air Quality. “Such an approach will present significant legal problems for the administration and manufacturers.”

EPA and NHTSA set aside their tug of war over the standards and reached an agreement with the California Air Resources Board and automakers under the Obama administration.

EPA has dozens of staff members and a lab in Ann Arbor, Mich., dedicated to regulating tailpipe emissions. It led an analysis of available technology and found that automakers could meet the standards at a lower cost than previously projected. Citing the report at the end of the Obama administration, EPA moved alone, without NHTSA, to lock in the standards for 2022 to 2025.

Since the beginning, the Trump administration has instead bolstered NHTSA's role while minimizing EPA's. When Trump announced he would reverse EPA's decision and reopen the standards, EPA staff were not consulted or brought to the announcement.

“It is a little bit disturbing that EPA may be abdicating that responsibility and relying too much on NHTSA,” said Shannon Baker-Branstetter, policy counsel for Consumers Union. “They're both important.”

Yesterday's notice asks for specific feedback on “the advantages or deficiencies in EPA's past approaches to forecasting” and “the impact of the standards on consumer behavior.”

Automakers, which want to avoid a patchwork of regulations and have urged NHTSA to reclaim its leadership on the standards, welcomed what they saw as the fulfillment of an administration promise.

“We're delighted to see the two federal agencies align and coordinate their programs, and we thank Secretary Chao and Administrator Pruitt for working closely together to harmonize a review driven by the most current data, consumer preferences and marketplace realities,” Mitch Bainwol, CEO of the Alliance of Automobile Manufacturers, said in a statement.

Reprinted from Climatewire with permission from E&E News. E&E provides daily coverage of essential energy and environmental news at