American drivers are consuming less and less fuel, following a trend of reduced car ownership and distance traveled, according to a new report by the University of Michigan Transportation Research Institute (UMTRI).

The findings show that overall fuel consumption among light-duty vehicles fell 11 percent over a recent seven-year period. Light-duty vehicles consumed 123.9 billion gallons of gasoline in 2011, down from a peak of 138.8 billion gallons in 2004.

Fuel consumption rates per person, per licensed driver, per household and per registered vehicle fell even more sharply and are now below where they were in 1984. Each of these rates peaked in 2003 or 2004, ahead of the 2008 financial recession, and fell 13 to 17 percent by 2011.

"Given that the maxima in the fuel-consumption rates occurred several years prior to the onset of the current economic downturn, these maxima have a good chance of being permanent peaks," said Michael Sivak, a research professor at UMTRI and author of the report.

Earlier reports have also found driving rates to be dropping even as the U.S. economy regains momentum (ClimateWire, Aug 29). While the exact cause is not known, experts point to urbanization, an increase in public transit use and new technologies like teleconferencing as the source of the decline.

The UMTRI report is the latest report in a series of studies. Earlier research found that the overall number of registered light-duty vehicles in the United States peaked in 2008 and the number of registered vehicles on a per-capita basis peaked in 2006. Sivak also found the number of vehicle miles traveled peaked in 2004 and declined 5 to 9 percent per person, per licensed driver, per household and per registered vehicle by 2011 (ClimateWire, July 29).

According to Sivak, the steeper drop in fuel consumption over the corresponding decrease in distance driven -- 13 to 17 percent versus 5 to 9 percent -- reflects an improvement in vehicle fuel efficiency.

'Rebound effect' didn't happen

Deron Lovaas, federal transportation policy director for the Natural Resources Defense Council, said the UMTRI findings show that federal policies are paying off. Under new corporate average fuel economy standards set by the Obama administration, light-duty vehicles must reach a fleetwide average of 34.1 mpg by 2016 and 54.5 mpg by 2025.

"Efficiency is being driven in part by policy. It's not happening by accident; it's happening partly because of economics and partly because of design," Lovaas said. "This is affirmation of the importance of those drivers."

But policy isn't the only factor at play, he admitted.

Regulations were expected to improve vehicle efficiency; the surprise is in the corresponding drop in vehicle miles traveled.

"It seems to turn the conventional wisdom about a rebound effect on its head. People say you increase efficiency and you'll necessarily get a big increase in energy use, and there are various assessments of how big that rebound effect is. But we're seeing increased efficiency and reduced driving," Lovaas said. "Basically, efficiency and reduced driving are in the ring with oil dependence, and they've struck a double blow against it."

A decrease in oil consumption is a win for consumers who pay for gasoline at the pump and helps bolster the fight against climate change. However, it presents a problem for a transportation network that relies on the federal gasoline tax to fund upgrades and expansions, said Lovaas. The gas tax-supported U.S. Highway Trust Fund is rapidly dwindling and is headed for bankruptcy in 2014.

"The trade-off is [reduced oil consumption] exacerbates the problems of the transport program that's dependent on ever more driving and fuel consumption," he said. "It turns out it intensifies the need to find a new solution for our transportation funding problem."

Reprinted from Climatewire with permission from Environment & Energy Publishing, LLC. www.eenews.net, 202-628-6500