U-M data
The University of Michigan released it's average new car fuel economy for the month of August today, and likely due to a surge in gasoline prices, average new vehicle fuel efficiency rose.

The average new vehicle sold in August had a fuel economy of 23.8 miles per gallon, a 0.2mpg increase from July, and up 3.7mpg from when the study began in 2007.

In addition to the fuel economy study, the University also estimates the average amount of emissions generated by each motorist for the month. That index stood solid in June, the last month for which data is available, at 0.82. The number is found proportionally compared to October, 2007, for which is the first month the study was performed.

Average fuel economy of new vehicles sold hit a high in March at 24.1mpg, just as gasoline prices peaked, before dropping each month until bottoming out in June and July. It comes as no surprise that the index rose as gasoline prices saw their largest August increases ever.