The average fuel economy of new U.S. light vehicles sold in March rose to 25.4 mpg, according to University of Michigan researchers, the highest since they began collecting data in October 2007.
The 25.4 mpg figure is up 0.3 mpg from the revised figure for February and 5.3 mpg from the October 2007 average, a monthly report from the university's Transportation Research Institute said.
Average sales-weighted fuel economy was calculated using the monthly sales of individual models and the combined city-highway fuel economy ratings from the EPA Fuel Economy Guide for each model.
In a separate study, fuel consumption by American drivers was found to be 11 percent lower in 2012 than in 2004. The reduction, said researcher Michael Sivak, "reflects the decline in distance driven and the improvement in vehicle fuel economy."
He said: "The combined evidence from this and the previous studies indicates that -- per person, per driver and per household -- we now have fewer light-duty vehicles, we drive each of them less and we consume less fuel than in the past."