Photo via Wikipedia.

Photo via Wikipedia.

The average fuel economy of new vehicles sold in October fell 0.4 mpg to 24.8 mpg, according to the University of Michigan's Transportation Research Institute (UMTRI).

The move likely reflects "a continuing increase in the proportion of light trucks sold each month, as well as the recent calculation adjustments for window-sticker values implemented by the EPA for model year 2017," according to UMTRI researchers Michael Sivak and Brandon Schoettle.

The institute has been tracking EPA window sticker fuel economy data since October of 2007. The value for October is up by 4.7 mpg since October of 2007.

The University of Michigan Eco-Driving Index (EDI) — an index that estimates the average monthly emissions of greenhouse gases generated by an individual U.S. driver — was 0.81 in August, down 0.01 from the value for July (the lower the value the better).

This value indicates that the average new-vehicle driver produced 19% lower emissions in August than in October 2007, but 3% higher emissions than the record low reached in both August of 2014 and August of 2015.