The U.S. National Academy of Sciences is worried that it might have overestimated the amount of fuel savings possible if automakers were to redesign their vehicles. The academy is holding a public hearing in early October to consider changing a report issued this summer that found that fuel economy of some vehicles could be boosted as much as 40 percent without requiring big reductions in size or weight. The Alliance of Automobile Manufacturers, however, says the academy may have double-counted the efficiencies of some technologies to come up with the 40 percent figure.

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