Soaring prices at the pump apparently are having such a dramatic impact in the U.S. that annual gas consumption is expected to drop for the first time in nearly two decades — meaning Americans not only are driving less, they're doing it more efficiently.

The Transportation Department reported Wednesday that Americans drove 1.8 percent fewer miles in April, compared with the same month last year, the sixth consecutive month driving miles figures have declined.

Those numbers represent a significant shift in consumer behavior, according to a report on driving habits and energy consumption by Cambridge Energy Research Associates. The report says Americans not only are changing their driving habits, they're shunning SUVs, pickup trucks and minivans, sending sales of those vehicles plunging more than 50 percent this year. Drivers instead are buying smaller, more fuel-efficient vehicles, including hybrids.

"It's kind of stunning," the study's co-author, Aaron F. Brady, told the New York Times. "It's like falling off a cliff.

The study also cites changing driving habits — more car-pooling, elimination of unnecessary trips, greater use of public transportation — as reasons for the drop in gasoline consumption, the Times reports.

The study also says that the national price for unleaded gas would need to average $4.23 a gallon to "create the same economic pain as in 1981," the Times reported.

"Once unthinkable, such a level is now within view," the report said.

Click here to read the complete New York Times story.

Meanwhile, the Transportation Department report found that Americans drove 30 billion fewer miles — about a 1 percent decline — from November 2007 to April 2008, the largest drop since the gas shortages of the late '70s.