Study Shows Hybrids Are Not Improving US Fleet Mileage. Study shows average fuel economy for the US vehicle fleet has improved less than 1 MPG in 22 years.

The Newspaper.com reports:

Supporters of toll roads insist that the gas tax can no longer be relied upon to fund roads because hybrid and electric automobiles are improving gas mileage so much that gas tax receipts are down. A study released last week by the University of Michigan Transportation Research Institute shows that, contrary to this assertion, the gas mileage of the US car and truck fleet has changed very little over the past two decades.

Researchers Michael Sivak and Brandon Schoettle pulled together data estimating the miles driven per gallon of fuel from 1923 to 2013. They divided the results into several distinct periods.

In the first, from 1923 through 1935, vehicles recorded a more or less constant 14 MPG. In 1936, fuel economy began a slide to 11.9 MPG in 1973, when the oil embargo struck. This sparked an emphasis on fuel economy that lasted until 1991, increasing to 16.9 MPG, representing a compound annual gain of 2.4 percent. In the current period, fuel economy for all vehicles rose to just 17.6 MPG by 2013 — a compound annual gain of just 0.8 percent. Even excluding trucks and counting only automobiles, the average MPG has only risen 2.2 MPG in the past twenty-two years.

“One fundamental problem with improving the fuel economy of the entire on-road fleet is that improvements in fuel economy of new vehicles take a long time to substantially influence the fuel economy of the entire fleet,” the report explained. “This is the case because it takes many years to turn over the fleet.”

Just a reminder.