The U.S. Environmental Protection Agency (EPA) and the National Highway Traffic Safety Administration (NHTSA) adopted the first U.S. standards to reduce greenhouse gas (GHG) emissions and improve the fuel efficiency of medium- and heavy-duty vehicles. The EPA’s program to reduce GHG emissions begins with model year 2014 vehicles and does not have an end date while the NHTSA’s mandatory program to improve fuel efficiency starts in 2016 and ends in 2019.
