In its monthly release, the University of Michigan Transportation Research Institute reports that the average fuel economy of new vehicles based on their window sticker values was 24.9 mpg in December, down 0.1 mpg from the revised rating in November. The institute considers the change to likely be a reflection of the increasing proportion of light trucks that are being sold.
Overall, fuel economy ratings were down 0.6 mpg from a peak of 25.5 mpg in August 2014 but remain up 4.8 mpg from a low of 20.1 mpg recorded when monitoring began in October 2007.
The University of Michigan Eco-Driving Index (EDI) was 0.83 in October, unchanged from September. The index estimates the average emissions of greenhouse gases generated by U.S. drivers on a monthly basis.
Taking into account a combination of fuel economy and driving distance, the EDI value indicates that on average, new-vehicle drivers produced 17% lower emissions in September compared to October 2007, but 4% more greenhouse gases than a record low last reached in November 2015.