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Vehicle Technologies Office: Advanced Combustion Engines

Improving the efficiency of internal combustion engines is one of the most promising and cost-effective near- to mid-term approaches to increasing highway vehicles' fuel economy. The Vehicle Technologies Office's research and development activities address critical barriers to commercializing higher efficiency, very low emissions advanced internal combustion engines for passenger and commercial vehicles. This technology has great potential to reduce U.S. petroleum consumption, resulting in greater economic, environmental, and energy security.

Already offering outstanding drivability and reliability to over 230 million passenger vehicles, internal combustion engines have the potential to become substantially more efficient. Initial results from laboratory engine tests indicate that passenger vehicle fuel economy can be improved by more than up to 50 percent, and some vehicle simulation models estimate potential improvements of up to 75 percent. Advanced combustion engines can utilize renewable fuels, and when combined with hybrid electric powertrains could have even further reductions in fuel consumption. As the EIA reference case forecasts that by 2035, more than 99 percent of light- and heavy-duty vehicles sold will still have internal combustion engines, the potential fuel savings is tremendous.

The Vehicle Technologies Office's Contribution

The Vehicle Technologies Office (VTO) undertakes research and development activities to improve the efficiency of engines for both light and heavy-duty highway vehicles, whether they run on petroleum-based (gasoline and diesel) or alternative fuels. We support every type of research in these areas, from fundamental science to prototype demonstration. VTO's research focuses on improving engine efficiency while meeting future federal and state emissions regulations through three main approaches:

Commercialization of these advanced combustion engine technologies could allow the U.S. to cut its transportation fuel use and corresponding greenhouse gas emissions by as much as 20 to 40 percent.

Research and development is done in collaboration with industry, national laboratories, other federal agencies (such as the National Science Foundation) and universities, as well as through government/industry partnerships:


The major goals of the Advanced Combustion Engine R&D subprogram are:

  • By 2015, increase the efficiency of internal combustion engines for passenger vehicles resulting in fuel economy improvements of 25 percent for gasoline vehicles and 40 percent for diesel vehicles, compared to 2010 gasoline vehicles. By 2020, improve the fuel economy of gasoline vehicles by 35 percent and diesel vehicles by 50 percent, compared to 2010 gasoline vehicles.
  • By 2015, increase the efficiency of internal combustion engines for commercial vehicles from 42 percent (2010 baseline) to 50 percent (a 20 percent improvement). This goal is part of the overall SuperTruck initiative to increase Class 8 truck freight hauling efficiency by more than 50% by 2015. By 2020, further improve engine efficiency to 55 percent (a 30 percent improvement) with demonstrations on commercial vehicle platforms.
  • By 2015, increase the fuel economy of passenger vehicles by at least 5 percent using thermoelectric generators that convert energy from engine waste heat to electricity.

These research and development activities are described annually at the Merit Review, the VTO-sponsored Directions in Engine-Efficiency and Emissions Research (DEER) Conference, and Progress Reports.