How fuel-efficient are the cars sold in the United States?

Published on October 14th 2019

California is suing the Trump administration for revoking its right to set its fuel economy standard. The state struck a deal earlier this year with four automakers to push for stricter measures, even as the administration freezes goals for future fuel economy standards at the current level. How far are we currently from either standard?

The US Department of Energy has compiled data on more than 41,000 passenger car models sold in the United States since 1984. While the information doesn’t account for the number of cars sold, it does show how fuel economy performance has increased over the past few decades. Averages remain below both the 51 miles per gallon that the California deal requires car companies to hit in 2026. It’s also below the 37 miles per gallon that the Trump administration has said it plans to require.

Overall improvement in fuel efficiency since 1984

The average miles per gallon across all car types, for city and highway combined, has increased from 20 mpg for the model year 1984 vehicles to nearly 26 mpg for 2019 vehicles.

Much of the increase in average miles per gallon comes from improvements in the fuel efficiency of sedans and SUVs. Pickup trucks have seen the smallest growth in fuel efficiency, from about 17 mpg for 1985 vehicles to 19 mpg for 2019 cars.

Many cars remain below the National Highway Traffic Safety Administration’s (NHTSA) Corporate Average Fuel Economy (“CAFE”) fuel economy standards set for vehicles by car size and model year (NHTSA).

The penalty to automakers for failing to meet the CAFE standard for a vehicle is $5.50 for every 0.1 mpg a vehicle is below the CAFE standards. That value is multiplied by the number of vehicles in the manufacturer’s fleet, a fee that has increased from $5.00 in 1997 (NHTSA). In 2019, some policymakers advocated for increasing the penalty from $5.50 to $14. This change was rejected by the Department of Transportation and the National Highway Traffic Safety Administration due to the rule’s projected negative economic impact (OMB). In total, automakers have paid more than $890 million in CAFE civil penalties for all vehicles up to the model year 2015 (NHTSA).

While the average fuel economy has been improving particularly for sedans and station wagons, the range of fuel efficiencies has widened within each fuel type. For example, in 1984, sedans had a fuel efficiency range of 8 mpg to 41 mpg; in 2019, the range widened to a low of 13 mpg and a high of 136 mpg. The most fuel-efficient 2019 models were both electric vehicles: the Hyundai Ioniq Electric, with 136 mpg, and the Tesla Model 3 Standard Range Plus, with 133 mpg.

The impact of alternative fuels and electric vehicles on improved fuel efficiency

A large part of the improvement in fuel efficiency, as well as the dramatic increase in the maximum fuel efficiency of vehicles, has been driven by the shift towards alternative fuel types such as electricity and hybrid fuels. For example, in 1998, there were only three electric vehicle models to choose from — the Honda EV Plus and two versions of the Chevrolet S10 Electric. These cars make up less than 2% of all 1998 models. In 2019, there were 36 electric vehicle models to choose from, making up over 17% of all 2019 models.

While electric vehicles began with a fuel efficiency of about 50 mpg, similar to hybrids like the Honda Insight and Prius, they’ve since outpaced hybrids with an average of more than 100 mpg. Hybrids average about 33 mpg.

Fuel efficiency improvement by brand

Here’s how some vehicle brands have — or haven’t — made fuel economy improvements, according to the Department of Energy. Brands that have diversified fleets to include several electric vehicles have especially made progress.

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Notes

Electric vehicle fuel efficiency is calculated as MPGe, or gasoline-equivalent miles per gallon—the number of miles a vehicle can go using a quantity of fuel that has the same energy that’s in as a gallon of gasoline. (EPA). For example, an electric vehicle with 34 kW-hrs per 100 miles has an MPGe of 99 (EPA)

Sources

Department of Energy, FuelEconomy.gov