The Obama administration has approved a rule setting stricter goals for medium- and heavy-duty truck fuel consumption and carbon emissions, phased in through 2027.

The final rule, which the Environmental Protection Agency Administrator Gina McCarthy and Dept. of Transportation Secretary Anthony Foxx signed on Aug. 16, will reduce carbon emissions by 1.1 billion tons and save truck operators an estimated $170 billion in motor-fuel expenses, the White House says.

The 1,690-page regulation is the second phase of the Obama administration’s regulations covering such large trucks. It mandates carbon-emissions cuts of as much as 25% from levels set in the phase-one rules—issued in 2010—which apply to trucks from model years 2014 through 2018.

EPA's McCarthy told reporters in a conference call, “These standards are ambitious and achievable.” (See fact sheet.)

The regulation will take effect 60 days after it is published in the Federal Register, but McCarthy noted that the requirements will take hold in three steps—in 2021, 2024 and 2027—“providing lead time and multiple pathways to compliance.”

She also said that, in each phase, there is a “total vehicle standard and a separate engine standard nested within it.” The benchmarks for diesel engines require emissions and fuel-use cuts of as much as 5%, compared with phase one.

DOT's Foxx said the final rule requires 10% greater emissions and fuel-consumption reductions compared with a proposal that EPA and DOT issued in July 2015.

Along with the new EPA-DOT rule, the administration announced $137 million in new Dept. of Energy funding for energy-efficiency technology for trucks.

Allen Schaeffer executive director of the Diesel Technology Forum, Frederick, Md., said engine and truck manufacturers have been making environmental and fuel-saving gains. He said in a statement that new diesel trucks put in service in the 2007-2015 period saved about 3 billion gallons of fuel and “delivered significant emissions reductions.”

The new regulation “raises the bar” for the industry, he said. The requirements “establish a bold challenge to further increase fuel efficiency and reduce greenhouse-gas emissions to unprecedented levels from a wide range of commercial vehicles," Schaeffer added.

Officials at the American Trucking Associations expressed cautious optimism that the regulation’s goals will be met and that the phase-in wouldn’t be too disruptive to motor carriers and equipment manufacturers.

Glen Kedzie, ATA vice president and energy and environmental counsel, said in a statement, “We are pleased that our concerns, such as adequate lead time for technology development, national harmonization of standards and flexibility for manufacturers, have been heard and included in the final rule.”

Environmental groups praised the EPA-DOT rule. Rhea Suh, Natural Resources Defense Council president, called it “a win-win for businesses and our climate.”