Dan Becker says it's necessary to take into account the energy expended to produce the fuel.

NPR: Environmentalists Weigh In on Ethanol

Dan Becker, director of the Sierra Club's global warming project, takes a darker view.

NPR: 'Flex-Fuel' Concept Fails to Deliver on Potential

Mr. DAN BECKER (Director, Global Warming Project, Sierra Club): The auto companies by merely producing the vehicle qualify for a loophole that allows them to produce more gas guzzlers.

NPR: 'Flex-Fuel' Concept Fails to Deliver on Potential