Bigger cars are stalling progress on climate change, EPA study finds

American automakers and consumers are stymieing progress on cutting the carbon pollution that causes climate change, according to the findings from the Environmental Protection Agency’s 2022 Automotive Trends Report. Even though miles per gallon are gradually increasing within each vehicle weight class, the ongoing shift from sedans to trucks and SUVs, which are subject to lower fuel efficiency requirements — and to bigger trucks and SUVs than the ones that were popular in previous decades — canceled out much of the expected benefits.

Environmental and consumer advocates are expressing disappointment.

“The bottom line is fleetwide fuel economy didn’t improve,” Avi Mersky, a transportation researcher at the American Council for an Energy-Efficient Economy, said in a statement about the report, which analyzed data on cars sold in 2021 versus previous years. “That’s bad news for drivers at the pump and for the climate.”

“Some models got more efficient,” Mersky noted, “but with the automakers marketing large SUVs so heavily, they’re taking up more and more market share. The manufacturers are canceling out all the efficiency progress as they sell more large vehicles.”

The EPA sets average fuel-economy standards that require auto manufacturers to reach a certain miles per gallon for each class of vehicle. Partly as a result, since 1975, miles per gallon of cars sold in the U.S. have roughly doubled, cutting carbon emissions per mile in half. But the shift toward bigger models, which the agency allows to have lower average fuel-economy standards, has prevented those improvements from being even greater.

Last year, while the fuel efficiency in each weight category reached record highs, the shift toward heavier types of vehicles offset that progress. In 2021, all the new cars and trucks sold in the U.S. had the exact same overall efficiency, 25.4 miles per gallon, that was reached in 2020.

“In model year 2021, sedans and wagons fell to 26% of the market, well below the 50% market share they held as recently as model year 2013, and far below the 80% market share they held in 1975,” the EPA noted in the report. “Conversely, truck SUVs reached a record 45% of the market in model year 2021, and pickups increased to 16% market share.”

“Truck SUVs” refers to SUVs so large that they are classified as trucks, rather than light trucks, by the EPA, allowing them to meet a lower miles per gallon standard. As the Detroit Free Press reported in 2018, many new SUVs are often so big that they cannot fit into older houses’ garages. Their production increased by 6% in 2021, while sedan production declined by 5%.

“The automakers are both making fewer cars, in favor of trucks, and making those trucks themselves bigger,” Mersky told Yahoo News. “It is also worth noting that even within these categories, vehicle footprint has been creeping upward. ... There is no vehicle category where vehicle footprints (sizes) have remained steady or decreased. The average vehicle in all categories got larger. While most vehicle categories increased average [miles per gallon], the in-category rate of improvement was much lower than the standards would have required had there not been a large upsizing of the fleet."

While fuel efficiency regulation was started in 1971 to cut down on the conventional air pollutants like nitrogen oxide that come from tailpipes, it has become a key part of how the federal government attempts to reduce greenhouse emissions. Transportation is the single largest cause of U.S. emissions, and the United States has pledged in international climate change agreements to cut its emissions by 50% by 2030.

The Biden administration has finalized ambitious new increases in required fuel efficiency for model years 2024-2026, but climate experts and advocates are urging it to go further in the next round of standards, which will be proposed next March and will govern model years 2027 and beyond.

“The EPA could decrease the slope of the standards,” Mersky said, meaning that the difference in allowable fuel economy between larger and smaller cars would be reduced. And the agency could also create a minimum fleetwide average efficiency, so that if too many consumers switch to bigger classes of vehicle, the standards in that class have to be raised to meet the overall average.

“EPA would also be justified in adding a ‘backstop’ to these standards,” Mersky added. “This would be a minimum fleetwide fuel economy, which, if not met, would automatically tighten the fuel economy and emission standards on all vehicles.”

The EPA did not comment before publication on whether it is considering such a move. Any stricter new regulation risks being overturned by a future Republican administration. The Obama administration had required efficiency increases of more than 20% for model years 2016 through 2021, but the Trump administration rolled back those regulations. As a result of that policy change and the shift toward larger vehicles, the nationwide fuel economy increased only 5% during those years.

Climate change is not the only reason that many are bemoaning the trend toward bigger trucks.

Advocates of road safety note that taller cars make it harder for drivers to see pedestrians — especially children and wheelchair users — and heavier cars do more damage in collisions. This is a major reason that, according to the Governors Highway Safety Association, pedestrians’ share of traffic deaths increased from 13% in 2010 to 17% in 2020. “While pedestrian deaths have risen by 54% over the past decade, all other traffic deaths have increased by 13%,” the organization noted. In 2021, drivers killed 7,485 pedestrians, the most in 40 years.

A study published in September in the Journal of Safety Research found that in accidents in which children were hit by an automobile while walking or biking, passenger cars were the striking vehicle 62% of the time, but they resulted in only 19% of deaths, whereas SUVs were the striking vehicle in 16.9% of collisions with children, but were responsible for 40% of deaths. And in 2020, a study by the Insurance Institute for Highway Safety found that 100% of pedestrians hit by SUVs going 40 mph or faster died, while 54% of those who were hit by cars going as fast died.

The Alliance for Automotive Innovation, which is the lobbying group for automakers, declined to comment for this story, but it pointed out that the industry is making progress in one key area: electric vehicles. There are now 83 electric-vehicle models available for sale in the U.S. Between 2020 and 2021, EVs’ share of U.S. new auto sales doubled, from 2% to 4%, and they are on pace to increase significantly again this year. In the second quarter of 2022, they accounted for 6.6% of new light-duty vehicle sales.