Potential for energy savings in old and new auto engines

This paper disucsses the potential for energy savings in the transportation sector through the use of both improved and entirely new automotive engines. Although spark‐ignition and diesel internal combustion engines will remain the dominant choices for passenger‐car use throughout the rest of this century, improved versions of these engines (lean‐burn, low‐friction spark‐ignition and adiabatic, low‐friction diesel engines) could, in the long term, provide a 20–30 percent improvement in fuel economy over what is currently available. The use of new materials, and modifications to both vehicle structure and vehicle transmissions may yield further improvements. Over a longer time frame, the introduction of the high‐temperature gas‐turbine engine and the use of new synfuels may provide further opportunities for energy conservation.