Gas mileage among the nation’s newest car models is at an all-time high, according to research conducted by the University of Michigan Transportation Research Institute.

The average EPA-rated fuel economy of new cars, light trucks, SUVs and minivans purchased in October was 24.1 mpg, a 20 percent bump from October 2007, when the university began tracking fuel efficiency. Average fuel economy in September 2012 was 23.8 mpg.

"The improvement in fuel economy in the past five years corresponds to a 17 percent reduction in fuel consumption per distance driven," said Michael Sivak, a research professor at the institute.

The new figures are consistent with other reports of increased overall fuel efficiency. The first half of 2012 saw an average of 23.8 mpg in the U.S., which was a 1.1-mpg improvement over the same period in the previous year.

What’s behind the uptick? The number of fuel-efficient models of small and midsized cars and crossovers has doubled since 2009, according to Automotive Fleet. The 2013 Ford Fiesta, for example, gets 38 mpg highway while the Nissan Versa logs 36 mpg.

Those numbers are likely tied to efforts by the federal government to curtail oil consumption. In 2007, the Energy Independence and Security Act was passed, which required cars, light trucks and SUVs to achieve a combined average of 35 mpg by 2020.

Then in 2010, the Transportation Department’s Corporate Average Fuel Economy standards mandated a 34.1-mpg average efficiency for model year 2016 vehicles. This past August, another set of CAFE requirements set an average of 54.5 mpg by 2025.

[Sources: The New York Times, Union of Concerned Scientists]