As national priorities have been focused both on reducing fuel consumption and improving air quality, attention has increased on reducing emissions from many types of vehicles, including light-duty, medium-duty, and heavy-duty diesel-powered vehicles. Meeting the recently promulgated (and proposed) emission standards and simultaneously increasing fuel economy will pose especially difficult challenges for diesel-powered vehicles and will require the development of new emission-reduction technologies. In response to a request from the director of OHVT, the National Research Council formed the Committee on Review of DOE's Office of Heavy Vehicle Technologies to conduct a broad, independent review of its research and development (R&D) activities.

In legislation appropriating funds for DOE's fiscal year (FY) 2000 energy R&D budget, the House Interior Appropriations Subcommittee directed an evaluation of the benefits that have accrued to the nation from the R&D conducted since 1978 in DOE's energy efficiency and fossil energy programs. In response to the congressional charge, the National Research Council formed the Committee on Benefits of DOE R&D on Energy Efficiency and Fossil Energy. From its inception, DOE's energy R&D program has been the subject of many outside evaluations. The present evaluation asks whether the benefits of the program have justified the considerable expenditure of public funds since DOE's formation in 1977, and, unlike earlier evaluations, it takes a comprehensive look at the actual outcomes of DOE's research over two decades.