Although the average fuel economy for new 2013 light-duty vehicles dipped slightly in June, the general trend — both for the year and historically — is steadily upward. That's according to the University of Michigan Transportation Research Institute, which calculates the average sales-weighted fuel economy using monthly sales of individual models of cars, SUVs, vans and pickup trucks as well as respective models' ratings published in the EPA Fuel Economy Guide.
Compared with the same period in 2012, the average fuel economy for light-duty vehicles in June was up by 1.2 mpg to 24.7 mpg. That's despite a small dip from May, when the average was 24.8. The overall fuel economy for model-year 2013 vehicles so far is 24.6 mpg. Since the institute started tracking the numbers in October 2007, the average fuel economy has improved by 4.6 mpg, steadily increasing by an average of 0.65 mpg per year.
Meanwhile, motorists' greenhouse-gas emissions also are declining, according to the University of Michigan's Eco-Driving Index, which estimates the average monthly amount of greenhouse gases produced by an individual U.S. driver who has purchased a new light-duty vehicle that month. The EDI for April stands at 0.82, indicating an 18% reduction since October 2007.