ANN ARBOR (WWJ) –  Fuel economy of all new vehicles sold in the United States last month was at its highest mark ever, researchers at the University of Michigan Transportation Research Institute announced Monday.

Average fuel economy of cars, light trucks, minivans and SUVs purchased in January was 23.0 miles per gallon, which ties the all-time monthly record set in March 2011. It is also up 4 percent (0.8 mpg) from December, the highest monthly increase since UMTRI researchers began tracking fuel economy in late 2007.

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According to Michael Sivak, research professor and head of UMTRI’s Human Factors Group, average fuel economy of all new vehicles bought last month was up 0.5 mpg from a year ago and is now 2.5 mpg higher than four years ago in January 2008.

In addition to average fuel economy, Sivak and UMTRI colleague Brandon 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.

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During November 2011, the EDI stood at 0.86, up from 0.85 in October, but down from 0.87 in September. The index currently shows that emissions of greenhouse gases per driver of newly purchased vehicles are down 14 percent since October 2007.

Fuel economy calculations, along with a graph and table of current and recent MPGs, are at

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Eco-Driving Index calculations, along with a graph and table of current and recent values, are at