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

The average fuel economy (window-sticker value) of new vehicles sold in January was 25.1 mpg—up 0.1 from December, but the same mark as January 2014 and January 2015.

Overall, fuel economy is down 0.4 mpg from the peak of 25.5 mpg reached in August 2014, but still up by 5.0 mpg since October 2007—the first full month of monitoring by 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.

During November, the EDI remained unchanged at 0.83 (the lower the value, the better) for the third month in a row. The index currently shows emissions of greenhouse gases per driver of newly purchased vehicles are down 17 percent, overall, since October 2007—but 5 percentage points higher than the record low reached in November 2013.

More information:

• Fuel economy
• Eco-Driving Index
• Michael Sivak
• Brandon Schoettle