ANN ARBOR—Gas mileage of new vehicles sold in the U.S. slipped last month, according to researchers at the University of Michigan Transportation Research Institute.

Average fuel economy (window-sticker values) of cars, light trucks, vans and SUVs purchased in April was 25.2 mpg, down from 25.4 mpg in March.

“This drop likely reflects the increased proportion of pickup trucks and SUVs in the sales mix,” said Michael Sivak, a research professor at UMTRI.

Fuel economy is now down 0.6 mpg from the peak reached in August 2014.

Overall, fuel economy is up 5.1 mpg from October 2007, the first full month of monitoring by Sivak and colleague Brandon Schoettle.

However, the average vehicle fuel economy during the first seven months of this model year (October 2014 through April 2015)—25.3 mpg—has stayed the same as during the preceding model year (October 2013 through September 2014).

In addition to average fuel economy, Sivak and Schoettle issued a monthly update of their national Eco-Driving Index, which estimates the average monthly emissions generated by an individual U.S. driver. The EDI takes into account both the fuel used per distance driven and the amount of driving—the latter relying on data that are published with a two-month lag.

During February, the EDI remained at 0.82 (the lower the value, the better) for the second straight month. The index currently shows emissions of greenhouse gases per driver of newly purchased vehicles are now down 18 percent, overall, since October 2007.

More information:

• Fuel economy (with graph and table of current/recent mpg)
• Eco-Driving Index (with graph and table of current/recent values)
• Michael Sivak
• Brandon Schoettle

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.