Energy use of light-duty vehicles is expected to decline between 2018 and 2040 as fuel economy improvements more than offset the projected rise in the number of miles they are driven, according to the U.S. Energy Information Administration. Impacts on fuel economy and the number of miles traveled account for the expected changes in energy consumption by these vehicles.
In 2016, light-duty vehicles, which include light trucks and passenger cars, traveled a record of 2.84 trillion miles in the United States. By 2040, light-duty vehicles are expected to travel 3.33 trillion miles.
New vehicles account for a small amount of the total number of light-duty vehicles in any year, and “existing vehicles can remain on the road for many years,” according to the EIA. However, “fuel economy standards for new vehicles and the mix of vehicles purchased have long-term implications for fuel consumption.”
The National Highway Traffic Safety Administration and the Environmental Protection Agency set standards for fuel economy and greenhouse gas emissions, and the standards are stricter for passenger cars compared to light trucks. For the 2015 model, fuel economy standards for cars were about 35 miles per gallon, but for trucks, they were 27 mpg. By 2025, the standards will be 53 mpg for cars and 38 mpg for trucks.
While the federal agencies set the standards, the actual or on-road fuel economy of the vehicles differs from the standards. For the 2015 model, on-road fuel economies for passenger cars were about 31 mpg, compared to 21 mpg for trucks. Between 2015 and 2025, the on-road fuel economy for the cars is expected to rise 43% to 45 mpg, from 31 mpg. For light trucks, the on-road fuel economy should rise 46% to 31 mpg, from 21 mpg, in the same period.
As a result of the rise in fuel efficiency, vehicle energy consumption is expected to decline 12% to 14.2 quadrillion British thermal units in 2025, from 16.1 quadrillion Btu in 2017, even as the number of miles vehicles travel is expected to rise 5% over the period. The majority of the energy consumption is gasoline, and gas usage is expected to fall 13% to 7.5 million barrels per day in 2025, from 8.7 million barrels per day in 2017.