Topics / U.S. passenger vehicle technology trends

Under efficiency standards adopted in 2012, the U.S. passenger vehicle fleet must achieve an average fuel economy of 49.1 miles per gallon in 2025, or 54.5 mpg as measured in terms of carbon dioxide emissions with various credits for additional climate benefits factored in. While the fleet-average targets will change—the regulation provides for recalculating the fuel economy targets annually based on the mix of cars, pickups, and SUVs actually sold—they will still represent an average energy-efficiency improvement of 4.1% per year.

Automakers have responded by developing fuel-saving technologies even more rapidly and at lower cost than the U.S. EPA and NHTSA projected in 2011–2012, when the supporting analyses for the 2017–2025 rule were developed. In particular, innovations in conventional (as opposed to hybrid or electric) power trains and vehicle body design are significantly outpacing initial expectations.

The ICCT collaborated with automotive suppliers in a series of working papers that highlights many of the important innovations and trends in those conventional technologies.

The ICCT then summarized each working paper in a series of technology briefs, with additional assessment of the policy implications of the technological improvements. (The hybrid brief was written solely by the ICCT, but, like the others, is detailed technology assessment.)

Most Recent

Highlights important innovations and trends in diesel engines and emission control systems, some of which were not considered when the 2025 CAFE and greenhouse gas standards were finalized, yet promise to improve diesel passenger vehicles’ cost-effectiveness, especially for larger classes.

Diesel engines, aftertreatment, and emissions control have developed since 2012, improving diesel vehicles’ cost-effectiveness, particularly for larger passenger vehicle classes.

Reviews the political science, regulatory, and economics literature to illuminate the international competitiveness impacts of motor vehicle emission standards.


An analysis of trends and developments in thermal management technology since the 2017–2025 light duty GHG/CAFE rule written by EPA and NHTSA in 2012.

Publication: Working paper

This paper provides an analysis of transmission technology development and trends, and compares them to the projections made by EPA and NHTSA for the 2025 CAFE regulation.

Publication: Working paper

One in a series of technical briefs highlighting important innovations and trends in "conventional" automotive technologies, which are significantly outpacing projections made at the time the 2025 CAFE standards were finalized.

Publication: Briefing

Profiles and evaluates recent developments in naturally aspirated gasoline engine technologies, and compares them to the projections made by EPA and NHTSA for the 2025 CAFE regulation.

Publication: Working paper

Technical summary for policy makers of the status of hybrid vehicle development in the United States. First in a series of technical briefing papers on trends in energy efficiency of passenger vehicles in the U.S.

Publication: Briefing