The average fuel economy of light vehicles purchased in the U.S. in September had its largest decline in nearly three years, after hitting a record high in August, a University of Michigan Transportation Research Institute report said.
The average window-sticker rating of cars, SUVs, vans and pickups purchased last month was 25.3 mpg, down from August’s 25.8. The last time fuel economy dropped by 0.5 mpg was in December 2011, today’s report by researchers Michael Sivak and Brandon Schoettle said.
“This large drop likely reflects the increased sales of light trucks and SUVs and the reduced demand for fuel-efficient vehicles of all types because of the falling gas prices,” said Sivak, who also is a professor.
Total U.S. light-truck sales rose 17 percent last month, while light-car sales rose by just 2 percent.
Despite the drop from August, September’s fuel economy is up 0.8 mpg from a year earlier, and it was the eighth consecutive month that fuel economy was above 25 mpg. Average stated fuel economy is up 5.2 mpg from October 2007, the university’s first full month of monitoring, the report said.
The researchers’ sales data is for vehicle models only, Sivak said. Data was not broken down by specific engine or vehicle-model variant.
Another study by the institute tracked July’s average greenhouse gas emissions of each new-vehicle driver in the country. The Eco-Driving Index hit a record low 0.77, exceeding June’s low of 0.78. July is the third straight month that the index has fallen.
A lower index score is better, and the scores are compared with a base score of 1 in October 2007, when the data collection began. The study found that emissions of greenhouse gases per driver of newly purchased vehicles decreased 23 percent since that time.
The index score is based on the fuel used per distance driven and the amount of driving. The amount of driving comes from data that are published with a two-month lag, the report said.