It's debatable whether Cash for Clunkers did any widespread good, but the program has had a visible affect on what Americans drive.  Ward's Auto reports, "Consumers went for miles-per-gallon in a big way in August, as U.S. light-vehicle sales achieved a record fuel-efficiency rating."  The average mpg of new cars purchased in August "hit a 23 mpg...up 1% from the previous high set in July," the first month of the Cash for Clunkers program. 

Autoblog adds, "As far as individual automakers go, Toyota came out on top with an average of 26.9 mpg for all cars sold in August, followed by Kia at 25.1 and Hyundai at 24.9 mpg. American nameplates made the biggest mileage jump, rising about four percent from August of 2008 to 20.4 mpg - a new record."

Green Car Reports thinks that the numbers may be the beginning of a trend.  "Average gas mileage will continue to rise as automakers adapt their products to meet new U.S. fuel economy standards of 42 mpg by 2016. To do that, they will fit smaller (but equally powerful) engines, some of them direct-injected and turbocharged, electronically controlled six-speed automatic transmissions, and other fuel saving gear," they speculate.

Autoblog sees a short-term drop, however, commenting, "Nobody knows exactly what will happen when the sales figures from September are calculated, but many experts are predicting that fuel efficiency will take a nosedive now that C4C will no longer be offering up to $4,500 to trade up to a new, more efficient car or truck."

If you're in the market for a new car, check out the U.S. News rankings of this year's best cars as well as this month's best car deals.