Still guzzling, but at a slower pace

Demographic factors may also weigh on gasoline consumption. In the 1950s and '60s, when the postwar march to the suburbs was in full swing and the nation's highways were being built out, gas consumption grew by an average of 4 percent a year. In more recent years, that rate has moderated to 1.2 percent. A study released in April by the EIA posited that part of the decline could be attributed to falling population growth and baby boomers exiting their peak driving years. That translates into fewer car sales. "What we were seeing is the automobile market is saturated," says Tancred Lidderdale, senior economist with the EIA. "Even as income continues to grow, we're not going to see the number of cars increase any further."

Mind you, it's not yet certain that falling gas consumption is a trend that's here to stay. Historically, consumption tends to dip during recessions, then rebounds after. "There have really only been a few times Americans have cut back their gas consumption over a long period of time," says Geoff Sundstrom, a spokesperson for AAA. "Those occasions are where you've had high prices and a recession, such as 1974 and 1981. It looks like we're heading into another one of those." In fact, the EIA's researchers expect that consumption growth will rise back up to 0.9 percent next year — though that's still below the 1.2 percent we've averaged so far this decade. Many analysts have been knocking down their estimates of worldwide oil demand growth, due in large part to weaker consumption in the U.S.

So even if gas consumption does bounce back, it's likely to do so at a much slower pace. "Consumer habits are pretty sticky," says Adam Robinson, an energy analyst at Lehman Brothers. "We've seen a long period of high prices that has finally hit the consumer, and now they're going to shift their preferences."

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Indeed, some commuters are surprised at how easily public transport can become habit-forming. Aly Cohen, a 27-year-old financial analyst at Costco Wholesale, first tried taking the bus to work in January after her car got stuck in the snow. Now, with her employer picking up most of the $63 tab for a monthly bus pass, she has stopped driving to work altogether and cut her gas consumption in half. "It's nice," she says. "I can take a nap or read." If copied on a large scale, such shifts in commuting habits may change the energy consumption game in the U.S.

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