The average fuel economy of new vehicles sold in the U.S. in December was 24.9 mpg, which declined 0.1 mpg from the revised value for November. This decrease in fuel economy likely reflects the continuing increase of light trucks sold, according to Michael Sivak and Brandon Shoettle from the University of Michigan.    

The value for December is up 4.8 mpg since October 2007 (the first month of UMTRI’s monitoring), but down 0.6 mpg from the peak of 25.5 mpg reached in August of 2014.

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 0.83 in October, unchanged from the value for September (the lower the value the better). 

This value indicates that the average new-vehicle driver produced 17% lower emissions in October than in October of 2007, but 4% higher emissions than the record low reached last time in November of 2015.