Photo via Wikimedia.

Photo via Wikimedia.

The average EPA fuel economy rating of new vehicles increased 0.2 mpg to 25.4 mpg in May, according to the University of Michigan's Transportation Research Institute (UMTRI).

The increase came as retail vehicle sales stalled during the month and likely came as a result of the increased price of gasoline and "the consequent increased interest in more fuel-efficient vehicles by buyers of all vehicle classes," according to UMTRI researchers Michael Sivak and Brandon Schoettle.

Fuel economy is down 0.4 mpg from the peak reached in August of 2014, but still up 5.3 mpg since October of 2007.

The University of Michigan's Eco-Driving Index (EDI), which estimates the average monthly emissions of greenhouse gases generated by an individual U.S. driver, was 0.84 in March 2016, up 0.03 from the value for February of 2016 (the lower the value the better).

This value indicates that the average new-vehicle driver produced 16% lower emissions in March of 2016 than in October of 2007, but 6% higher emissions than the record low reached in both August of 2014 and August of 2015.