Heavy-Duty Vehicle Fuel Efficiency and Greenhouse Gas Emissions: The 2014-2019 Standards and a Pathway to the Next Phase

Research Report T113


Siddiq Khan and Therese Langer


Heavy-duty vehicle standards, adopted by the Environmental Protection Agency and the National Highway Traffic Safety Administration in 2011, represent an important step toward reducing fuel consumption and greenhouse gas emissions of the transportation sector. The standards cover vehicles and engines of model years 2014 through 2019 and require fuel consumption reductions ranging from 5 percent to 24 percent for later years, depending on vehicle or engine class. The program will promote the adoption of certain efficiency technologies but not others, in part due to the structure of the program, which focuses on the efficiency of components rather than the vehicle as a whole.

The next phase of the program, to begin in 2020 or before, should be based on evaluation of the full vehicle. This will have major implications for tractor-trailers and vocational vehicles, and will allow the program to drive greater savings than the current program structure permits. Prerequisites for this next phase include more complete and up-to-date data on heavy-duty vehicle usage than is available today, as well as an enhanced simulation model. The program should also include finer segmentation of vocational vehicles and a test protocol based on physical testing complemented by vehicle simulation. Test cycles and payload for each class of trucks need re-evaluation. The program should also provide information to the public sufficient to enable buyers to choose vehicles best suited to their duty cycles.