Comparative Analysis of Automotive Powertrain Choices for the Next 25 Years

This paper assesses the potential improvement of automotive powertrain technologies 25 years into the future. The powertrain types assessed include naturally-aspirated gasoline engines, turbocharged gasoline engines, diesel engines, gasoline-electric hybrids, and various advanced transmissions. Advancements in aerodynamics, vehicle weight reduction and tire rolling friction are also taken into account.

The objective of the comparison is the potential of anticipated improvements in these powertrain technologies for reducing petroleum consumption and greenhouse gas emissions at the same level of performance as current vehicles in the U.S.A.

The fuel consumption and performance of future vehicles was estimated using a combination of scaling laws and detailed vehicle simulations. The results indicate that there is significant potential for reduction of fuel consumption for all the powertrains examined. More specifically, the current relative advantage of diesel over gasoline engines in terms of fuel consumption is likely to be reduced. Future turbocharged gasoline engines appear to have the potential to approach the fuel consumption levels of low emissions diesel engines. Hybrid electric vehicles will maintain a significant advantage over the other powertrains in terms of reduction of fuel consumption. This relative advantage is larger for urban than for highway driving. The details of the methodology used and the results obtained for a U.S. midsized car and a pick-up truck are presented