ANN ARBOR—Although fuel economy of all new vehicles sold in the United States dipped slightly last month, 2012 was the best year ever for fuel efficiency, say researchers at the University of Michigan Transportation Research Institute.

For the year, average fuel economy (window-sticker values) of newly purchased cars, light trucks, minivans and SUVs increased nearly 6 percent (1.3 mpg) to a record annual high of 23.8 mpg, according to UMTRI researchers Michael Sivak and Brandon Schoettle.

Since 2008, the first full year of monitoring by Sivak and Schoettle, fuel economy has risen 14 percent—from 20.9 mpg that year to 21.6 in 2009, 22.1 in 2010 and 22.5 in 2011, and to its record mark in 2012.

On a monthly basis, fuel economy in December was 23.9 mpg, a slight drop from 24.1 mpg in November—likely reflecting the recent reduction in gas prices, the researchers say.

In addition to average fuel economy, Sivak and Schoettle issued their 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 vehicle fuel economy and distance driven—the latter relying on data that are published with a two-month lag.

During October, the EDI registered a record-low 0.79 for the second straight month and down from 0.84 a year ago (the lower the value, the better). The index currently shows that emissions of greenhouse gases per driver of newly purchased vehicles are down 21 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.