ICE: Dramatic Efficiency Gains Possible

Although internal combustion engines (ICE) have been used for more than a century, significant improvements in energy efficiency and emissions reduction are still possible.





Dramatic ICE Gains STILL Possible?

In fact, boosting the efficiency of internal combustion engines is one of the most promising and cost-effective approaches to increasing vehicle fuel economy over the next 30 years. The United States can cut its transportation fuel use 20%–40% through commercialization of advanced engines—resulting in greater economic, environmental, and energy security. Using these engines in hybrid and plug-in hybrid electric vehicles will enable even greater fuel savings benefits.

The Advanced Combustion Engine R&D subprogram of the U.S. Department of Energy’s Vehicle Technologies Program (VTP) is improving the fuel economy of passenger vehicles (cars and light trucks) and commercial vehicles (medium-duty and commercial trucks) by increasing the efficiency of the engines that power them. The subprogram’s goals, strategies, and some of its major accomplishments are described below.


Passenger and Commercial Vehicle Goals

More than 230 million cars and light trucks consume three quarters of U.S. highway transportation fuel, mostly as gasoline. Our strategy for the passenger vehicle sector is two-pronged: 1) demonstrate cost-competitive, production-ready vehicles with advanced gasoline engines that are at least 25% more efficient than conventional engines by 2014; 2) demonstrate cost-competitive, production-ready diesel passenger vehicle engines based on high-efficiency clean combustion technologies that are at least 40% more efficient than current gasoline engines by 2014.



  • Improve passenger vehicle engine efficiency 25%–40% by 2014
  • Improve commercial vehicle engine efficiency at least 20% by 2014
  • Achieve commercial engine cost, durability, and emissions targets


Medium-duty, Commercial Vehicles Use 25% of Fuel

Although they account for fewer than 5% of highway vehicles, medium-duty and commercial vehicles account for a quarter of the fuel used. These vehicles are big, and they are driven constantly. The trucking industry’s high fuel consumption and low profit margins give truck manufacturers a strong incentive to commercialize energy- efficient technologies. Over the past five years, commercial engine research and development (R&D) funded by VTP has saved more than 2 billion gallons of petroleum-based fuel, resulting in fuel cost savings many times greater than the federal investment. We aim to build on these results by demonstrating a 50%-efficient commercial engine in 2014, which represents a 20% improvement over today’s engines. Successful commercialization of this advanced engine has the potential to save an additional 1 billion gallons of fuel annually by 2020.