Originally Posted by 121097.pdf

Future Potential of Hybrid and Diesel
Powertrains in the U.S. Light-Duty
Vehicle Market
. . .
Diesel and hybrid technologies each have the potential to increase light-duty vehicle fuel economy by a third or more without loss of performance, yet these technologies have typically been excluded from technical assessments of fuel economy potential on the grounds that hybrids are too expensive and diesels cannot meet Tier 2 emissions standards. Recently, hybrid costs have come down and the few hybrid makes available are selling well. Diesels have made great strides in reducing particulate and nitrogen oxide emissions, and are likely though not certain to meet future standards. In light of these developments, this study takes a detailed look at the market potential of these two powertrain technologies and their possible impacts on light-duty vehicle fuel economy. . . .

Originally Posted by bwilson4web

http://www.ornl.gov/~webworks/cppr/y2004/rpt/121097.pdf

This is a fair evaluation of the respective technologies and how they together can improve US fleet mileage.

Bob Wilson