ANN ARBOR—Gas mileage of new vehicles sold in the U.S. was 24.8 mpg in December, the same as the average for all of 2013—the best annual mark ever, say researchers at the University of Michigan Transportation Research Institute.

Average fuel economy (window-sticker values) of cars, light trucks, vans and SUVs purchased last year was up 1.0 mpg from 2012 and 3.9 mpg from 2008, the first full year of monitoring, according to UMTRI researchers Michael Sivak and Brandon Schoettle.

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.

For the fourth straight month, the EDI tied its best mark at 0.80 (the lower the value, the better) during October, the seventh time that it has registered that low in the past two years. The index currently shows that emissions of greenhouse gases per driver of newly purchased vehicles are down 20 percent, overall, since October 2007.

Related Links:

• Fuel economy calculations, along with a graph and table of current and recent mpg: www.umich.edu/~umtriswt/EDI_sales-weighted-mpg.html
• Eco-Driving Index calculations, along with a graph and table of current and recent values: www.umich.edu/~umtriswt/EDI_values.html

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.