Americans see the development of 100-mpg (2.4-L/100 km) cars as one of the most powerful ideas for combating global warming and reducing U.S. dependence on foreign oil, a new survey finds.

The Santa Monica, CA-based X Prize Foundation says when asked to choose among six options to address climate change and global warming, 22% of Americans surveyed chose the development of a super-efficient 100-mpg vehicle, while 20% chose providing tax credits for solar and wind power as the next best idea.

Some 62% of respondents expressed a strong interest in purchasing 100-mpg vehicles and 76% thought such a development would be extremely or very important to the U.S.

“It is clear to most Americans that the need to conserve energy and to find alternative means to power our automobiles is important to national security, as well as to their pocketbooks,” Donald Foley, Automotive X Prize division executive director, says in a statement.

“The development of super-efficient vehicles is imperative if we are going to move beyond the incremental changes mandated by the federal government and those considered by Congress.”

The national survey of 1,000 registered voters, conducted July 25-29 by Greenberg Quinlan Rosner Research Inc., indicates a gender divide, with 38% of men seeing the primary benefit of super-efficient autos as saving money on gas, while 35% of women believe the biggest benefit of buying a 100-mpg car is in reducing pollution and global warming.

Consumers remain wary of the costs of owning a highly fuel-efficient vehicle, naming cost by more than a 2-1 margin over other reasons they would have doubts about buying such a car.

“Auto makers understand the price-sensitivity of the buying public, and developing a super-efficient vehicle will not exempt them from addressing this core consumer concern,” Foley says.

The Automotive X Prize will provide a multimillion-dollar purse to the teams that can design, build and bring to market 100-mpg or equivalent fuel-economy vehicles.

The competition is expected to culminate in a Tour de France-style road race traveling through multiple cities while broadcasting to a global audience in 2009 and 2010.

Some 31 teams from five countries so far have signaled their intent to compete for the prize.

Organizers say the competition has received the support of several key federal agencies.

These include the Department of Energy’s Argonne National Laboratory; Department of Transportation’s National Highway Traffic and Safety Admin; the Federal Highway Admin.; the Environmental Protection Agency’s Office of Transportation and Air Quality; and the California Air Resources Board.