When the folks at the University of Michigan Transportation Research Institute first began tracking the average fuel economy of new cars sold in the U.S., it was 20.1 mpg. That was in October 2007.
Six years and one month later, researchers Michael Sivak and Brandon Schoettle are happy to report that average new-car fuel economy has risen 23 percent, to 24.8 mpg.
As you'll see from the graph above, that progress hasn't been entirely straightforward. Fuel economy tends to surge at specific times of year -- most often in April/May and in August/September as refineries switch from regular to summer-blend gasoline and back again. Prior to the changeovers, fuel supplies get tight, pushing prices higher, which often makes new-car shoppers prioritize fuel economy.
Average fuel economy can also jump slightly later in the year, around October, as the new model-year vehicles roll out. Typically, those new models earn better fuel economy than their predecessors, which boosts the national average.
For those keeping score at home who might be worried that automakers won't reach the fleet-wide Corporate Average Fuel Economy goal of 54.5 mpg by 2025, note that CAFE reached an all-time high of 30.3 mpg in November. That's up nearly six miles from October 2007, when CAFE registered 24.7 mpg. (For a discussion of CAFE goals and how likely automakers are to meet them, click here.)
And last but not least, eco-enthusiasts will be happy to know that not only do Americans continue drive less, but also U.S. vehicle emissions are at a record low -- and in fact, the drop in emissions is outpacing the drop in driving. As of September 2013, Americans were driving about 95 percent as many miles as they did in October 2007. But while driving has fallen five percent over the past six years, emissions have tumbled 20 percent. To view UMTRI's complete Eco-Driving Index, click here.