NASCAR teams are testing their cars with a new ethanol-based fuel even as scientists and activists are coming forward to criticize it.

NASCAR Chairman Brian France announced in December that NASCAR was switching to U.S. ethanol. The subject came up this week as driver and owner Tony Stewart addressed the media in Charlotte with crew chief Darien Grubb.

“We are working on fuel,” Grubb said. “We have the new E85 coming this year. We need to make sure we get the mileage and performance when we get down to Daytona.”

While drivers and crews are worried about how far the ethanol will stretch, others have more widespread concerns about the fuel.

Michael Knight, a veteran media/public relations representative in motorsports, noted that four years ago IndyCar announced it was going to U.S. ethanol in a move that would help farmers and the environment. IndyCar said it was using corn fuel in association with a U.S. trade group, the Ethanol Promotion and Information Council. EPIC is gone now, and IndyCar gets all its ethanol from Brazil.

So much for helping farmers.

Dr. Diandra Leslie-Pelecky is the author of The Physics of NASCAR: The Science behind the Speed. In a news release, she said, “It is very difficult to find anyone in the energy field who will argue that corn ethanol is a sustainable fuel or a wise choice for the future. Corn is a high-maintenance energy source, and virtually no one not associated with the corn lobby is arguing that making corn production more efficient will make enough of a dent in the problem to be worthwhile.”

One of the touted benefits of ethanol is that it is a cleaner buring fuel. However, she says that isn’t exactly right, either.

“Since ethanol only contains two-thirds the energy (gallon for gallon), you have to use more ethanol than gasoline to go the same distance,” Leslie-Pelecky said. By the time that is factored in, pure ethanol actually produces more carbon dioxide for the amount of energy produced.

Former Vice President Al Gore, once a proponent for ethanol, has changed his stance. In a November article in The New York Times, Gore said, “First-generation ethanol, I think, was a mistake. The energy conversion ratios are at best very small. It’s hard once such a program is put in place to deal with the lobbies that keep it going.”

Two other issues are how much corn and how much farm land are being used for these initiatives.

A 2008 Time magazine story called the biofuel plan “environmentally disastrous.”

“The grain it takes to fill an SUV tank with ethanol could feed a person for a year, wrote Michael Grunwald. “Land is an incredibly precious commodity, and every acre used to generate fuel is an acre that can't be used to generate the food needed to feed us or the carbon storage needed to save us.”