Fuel economy worse in fall, winter thanks to higher share of new light trucks sold

October 23, 2017
Contact: Bernie DeGroat bernied@umich.edu

Pumping gas. (stock image)

ANN ARBOR—Fall and winter are a good time to buy a vehicle as dealers clear out inventory from the previous model year but it’s also the time of year when average fuel economy of new vehicle sales is at its lowest.

A new study by Michael Sivak and Brandon Schoettle of the University of Michigan Transportation Research Institute examined the monthly variations in the relative sales and fuel economy of cars and light trucks over the past 10 years.

The researchers found that gas mileage of all newly sold light-duty vehicles ranges from 23.1 mpg to 23. 4 mpg from September to February. From March to August, average monthly fuel economy of new cars and light trucks sold remains fairly constant at a higher rate—either 23.6 mpg or 23.7 mpg.

The reason? The share of less fuel-efficient light trucks sold is higher during fall and winter.

“Because cars tend to have better fuel economy than light trucks, the expectation was that there would be a positive correlation between the share of cars and the average fuel economy of all light-duty vehicles,” Sivak said.

According to the U-M report, the monthly share of car sales is highest during spring and summer, ranging from 46.7 percent to 48.4 percent from March to August. The monthly share of light-duty trucks sold is highest during fall and winter, ranging from 53.1 percent to 55.9 percent from September to February.


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