Photo via EveryCarListed/Flickr.

Photo via EveryCarListed/Flickr.

The average fuel economy of new vehicles sold in September remained unchanged from August at 25.3 mpg, according to Brandon Schoettle and Michael Sivak, researchers from the University of Michigan's Transportation Research Institute (UMTRI).

September is up 5.2 mpg since October of 2007 (the first month of monitoring), but still down 0.2 mpg from the peak of 25.5 mpg reached in August of 2014.

The average fuel economy for model year 2017 vehicles (sold October 2016 through September 2017) was 25.2 mpg, which increased from 25.1 mpg for each of the preceding three model years.

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 — improved to 0.81 in July, which was down from 0.83 in June.

The EDI indicates that the average new-vehicle driver produced 19% lower emissions in July than in October of 2007, but 3% higher emissions than the record low reached in November of 2013.