The U.S. Environmental Protection Agency (EPA) and the Department of Transportation’s (DOT) National Highway Traffic Safety Administration are jointly proposing new standards for medium- and heavy-duty trucks aimed at boosting fuel efficiency and cutting carbon emissions. Claimed is that the move will reduce the impacts of climate change, bolster energy security, and spur manufacturing innovation.

The agencies note that medium- and heavy-duty vehicles currently account for about 20% of greenhouse gas (GHG) emissions and oil use in the U.S. transportation sector, but only comprise about 5% of on-road vehicles. Globally, oil consumption and GHG emissions from heavy-duty vehicles are expected to surpass that of passenger vehicles by 2030, according to EPA and DOT. Through the G-20 and discussions with other countries, the U.S. is working with other major economies to encourage progress on fuel economy in other nations.

The proposed vehicle and engine performance standards would cover model years 2021-2027 and apply to semi-trucks, large pickup trucks, and vans, as well as all types and sizes of buses and work trucks. They would achieve up to 24% lower CO2 emissions and fuel consumption than an equivalent tractor in 2018, based on the fully phased-in standards for the tractor alone in a tractor-trailer vehicle. Specific technologies are not mandated.

The agencies are proposing efficiency and GHG standards for trailers for the first time. EPA’s trailer standards, which exclude certain categories such as mobile homes, would take effect in model year 2018 for certain trailers, while NHTSA’s standards would be in effect as of 2021. Noted is that technologies such as aerodynamic devices, lightweight construction, and self-inflating tires can significantly reduce fuel consumption by tractor-trailers.