ANN ARBOR, MI – A new study by University of Michigan researchers found the average fuel economy is 14% higher for MY-2012 vehicles than it was for MY-2008 vehicles. When compared with a recent study that says the U.S. vehicle fleet didn’t see real fuel-economy gains for roughly 26 years, this study shows a significant improvement in overall fuel economy in a short period of time.

The study found that for all 2012 light-duty vehicles offered for sale, average mpg is 21.5, compared with 18.9 mpg for model-year 2008 vehicles. The averages were 21.2 for 2011 model-year vehicles, 20.7 for 2010, and 19 for 2009.

Researchers found that for new vehicles actually purchased, average fuel economy is one-to-two miles per gallon higher, at 22.5 mpg for model year 2011 (the last full year of sales), 22.1 for 2010, 21.3 for 2009, and 20.8 for 2008.

"This implies that consumers tend to choose vehicle models with better fuel economy than the average of all vehicles available," said Brandon Schoettle of the U-M Transportation Research Institute. "The recent economic downturn, coupled with rising gas prices, has led to an increased interest in purchasing more fuel-efficient vehicles."

Researchers also analyzed data from the EPA to determine fuel-economy changes based on vehicle characteristics.

The study found an improvement of 2.8 mpg for cars, including station wagons, and a 1.6 mpg improvement for light-duty trucks, from model-years 2008 to 2012. Average fuel economy is currently 23.4 mpg for cars and 18.6 mpg for light trucks. For all 12 vehicle size classes between 2008 and 2012, the study found the greatest increase in mpg for station wagons, which had the highest average 2012 rating of 26 mpg, and 3.8 mpg for compact cars, at 25.6 mpg.

The lowest increases were for full-size vans, at an average 2012 mpg rating of 13.4 mpg, and a 0.4 mpg increase for small pickup trucks, which had the third-lowest average of 18.6 mpg.

One interesting finding was that the average fuel economy of hybrid vehicles actually dropped by 3 mpg between 2008 and 2012. When looking at engine types, diesel had, by far, the greatest improvement at 9.8 mpg. Conventional gasoline engines improved by 2.6 mpg.

The mpg of four-cylinder engines improved by 2.3 and the mpg of six-cylinder engines went up by 1.4. Vehicles with front-wheel drive had improved mpg of 3.4, and 2 mpg for four-wheel- or all-wheel-drive vehicles. In terms of transmission types, vehicles with automatic transmissions improved by 2.5 mpg, and mpg of those with manual transmissions improved by 2.8.