While the fuel efficiency of the new cars sold in the United States last month dropped somewhat last month, model-year 2013 vehicles are still more efficient by nearly 5% over last year’s models, say researchers at the University of Michigan Transportation Research Institute.

Average fuel economy (window-sticker values) of cars, light trucks, vans and SUVs purchased in June was 24.7 mpg—down from 24.8 mpg in the previous three months, according to UMTRI researchers Michael Sivak and Brandon Schoettle. Overall, this is up 4.6 mpg since October 2007, the first month of monitoring.

Fuel economy of model-year 2013 vehicles sold since October 2012 is 24.6 mpg, up 1.1 mpg from 2012 models.

In addition to average fuel economy, Sivak and Schoettle issued a monthly update of their national Eco-Driving Index, which estimates the average monthly emissions generated by an individual U.S. driver. The EDI takes into account both the fuel used per distance driven and the amount of driving—the latter relying on data that are published with a two-month lag.

During April, the EDI increased slightly to 0.82 from 0.81 (the lower the value, the better). The index currently shows that emissions of greenhouse gases per driver of newly purchased vehicles are down 18 percent, overall, since October 2007.

Fuel economy calculations and Eco-Driving Index calculations, along with a graph and table of current and recent values are available for public review.