ANN ARBOR—In the three years since a new standard for gas mileage has been in effect, automakers have surpassed it each year, improving new-vehicle fuel economy by about a mile per gallon annually.

In 2012, the U.S. Environmental Protection Agency and the National Highway Traffic Safety Administration announced the final standard governing new-vehicle Corporate Average Fuel Economy for model years 2017-2025. Since then, CAFE performance has exceeded projected levels for 2012, 2013 and 2014—the three years the current standard has been in effect.

Achieved CAFE performance topped anticipated levels by 0.2 mpg for model year 2012, 0.1 mpg for model year 2013 and 0.2 mpg for model year 2014.

In addition, CAFE performance has consistently increased annually from model year 2008 through model year 2014, say Brandon Schoettle and Michael Sivak of the U-M Transportation Research Institute. Overall, fuel economy improved by 5.3 mpg over these seven model years, from 25.5 mpg to 30.8 mpg.

“If the current trends in annual improvements continue, future achieved CAFE performance is expected to continue meeting or exceeding the projected performance levels— and desired greenhouse gas reductions—contained in the latest CAFE standards,” Schoettle said.

The new standard for fuel economy for vehicle model years 2017-2025 continues the current system of incremental increases in CAFE for new light-duty vehicles (cars, vans, SUVs and pickup trucks) for each model year, based on targeted decreases averaging about 5 percent per year in carbon dioxide output per mile.

The strategy of simultaneously regulating fuel economy and greenhouse gas emissions of new vehicles was introduced in the current standard, in effect for model years 2012 through 2016. These standards are projected to require average fleetwide performance levels of 35.5 mpg by model year 2016 and 54.5 mpg by 2025.

“These performance levels assume that CAFE targets will be met purely through fuel economy improvements,” Schoettle said. “However, it is likely that manufacturers will also use alternative credits not related to improvements in fuel economy to assist in reaching these goals.”

Related Links:

• Brandon Schoettle: http://bit.ly/1pGoBDl
• Michael Sivak: http://bit.ly/HZlMiS

U-M Sustainability fosters a more sustainable world through collaborations across campus and beyond aimed at educating students, generating new knowledge, and minimizing our environmental footprint. Learn more at sustainability.umich.edu.