and large are offsetting from more efficient models in the U.S. as sedan and wagon sale have plummeted. While are slowly gaining traction, and even though carmakers have increased the efficiency of new models, is being dragged down by pickups, and has stagnated at 25.4 miles per gallon in 2021 — the same as 2020, according to a from the EPA.

As we said earlier, the average fuel economy of the U.S. fleet stayed flat due to the popularity of trucks and (as well as other 4WD SUVs, or those weighing over 6,000 pounds), which have overtaken their more efficient car and wagon counterparts on the American market. Sedans and wagons made up just 26 percent of new car sales in 2021, down from 50 percent in 2013 and 80 percent in 1975.

Meanwhile, truck-based SUV sales were at a record high in 2021, accounting for 45 percent of the overall market. Pickup trucks made up 16 percent. Even though the market share of pickup trucks is still below that of sedans and wagons, the , and have remained at in the U.S., and have only shown incremental gains in fuel economy.

The says trucks and so-called truck SUVs only gained 0.1 and 0.3 miles per gallon, respectively, for the 2021 model year. And out of all the vehicle types the EPA looked at in detail in the report, trucks have the flattest efficiency gains along a timeline that goes back to 1975:

made the biggest gain in fuel economy with 3.9 mpg added in 2021, followed by “car SUVs” (in other words, car-based crossovers) with an extra 2.6 mpg. Sedans and wagons were not that far ahead of trucks with an increase of only 0.5 mpg, but these vehicles are already more efficient than trucks to begin with, coming in at an average of 32.2 mpg in 2021. For reference, carbon emissions are down overall, having fallen by 0.6 percent to a record low of 347 grams per mile driven in 2021.

But the average size and weight of cars is also going up, reaching a record of 4,289 pounds. This further offsets any efficiency gains. So despite steady gains in efficiency in certain vehicle types, and slightly better emissions across the industry, the U.S. fuel economy figures remain relatively static. It’s just hard to see the positive impact from fuel-efficient cars when so many people are skipping over these and buying big trucks and SUVs instead.