Abstract:Technical studies, market trends, automaker announcements, and forecast assessments suggest that two automotive technologies—hybrid and diesel—will be prominent contributors toward achieving environmental and energy goals. Technology advances have led to a dramatic penetration of diesels into the European automobile market, while vehicles with hybrid electric-gasoline drivetrains have begun to see modest commercialization in the United States and Japan. This study quantitatively compares hybrid and diesel models in the 2010 U.S. market to discuss the potential for these two technologies in helping to meet future emission and efficiency objectives. The findings suggest that hybrid and diesel technologies offer prominent benefits in terms of fuel economy, greenhouse gas emissions, and vehicle performance. Diesel vehicles offer comparatively less greenhouse gas emissions than hybrids and provide an apparent criterion pollutant emission trade-off. Both technologies would have to experience cost reductions to become more mainstream in the U.S. automotive market.