Progress on the vehicle efficiency front is happening slowly, but it is happening, and last month a new average high of 24.9 mpg based upon window stickers was reached for passenger vehicles sold in the U.S., and emissions are improving as well.

According to the University of Michigan Eco-Driving Index (EDI), as of June (latest info available), the average monthly greenhouse gases generated by individual U.S. drivers was at 0.81 in June, a 19-percent improvement since October 2007.

As for the window sticker mpg, this was up 0.1 mpg from July and up 4.8 mpg over October 2007 when researchers in Michigan began collecting results.

This data is specifically compiled by the University of Michigan’s Brandon Schoettle, project manager, Sustainable Worldwide Transportation, and Michael Sivak, Ph.D., director, Sustainable Worldwide Transportation.

A description of calculations and recent mpg values can be found at the university’s Eco Driving Index, and info about EDI, how it’s calculated, and the current and recent values can be found here.