EPA: Auto fuel efficiency remained flat in 2021

• However, the real-world carbon dioxide emissions of the new fleet of vehicles fell by 2 grams per mile from the previous year, to a record low of 347 grams per mile.
• Preliminary data for 2022 model year vehicles estimates that fuel efficiency will rise to 26.4 miles per gallon, but that emissions will fall to 331 grams per mile.

The big picture: While technological innovation in the auto industry has given the means to create vehicles that are more efficient, less efficient models have remained popular.

• "Innovation in the automobile industry has led to a wide array of technology available to manufacturers to achieve CO2 emissions, fuel economy, and performance goals," the report's executive summary stated.
• "Fuel economy has also increased in all vehicle types since model year 2008, however the market shift towards less efficient vehicle types has offset some of the fleetwide fuel economy and CO2 emission benefits that otherwise would have been achieved through improving technology," per the report.

• Among the large manufacturers of 2021 model year vehicles, Tesla's electric fleet had the fuel highest fuel economy and lowest — at zero — carbon dioxide emissions. Meanwhile, Stellantis, the automaker formerly known as Fiat Chrysler, had the highest emissions and the lowest fuel economy.

Go deeper: Fuel efficiency progress "is stalling" because of growth of SUVs