Thanks to the fiscal cliff bill signed into law last week, a blend of fuel that contains more ethanol could soon reach more consumers than ever. That's bad news, AAA tells car owners.

The nation's largest motor club says use of the fuel blend, E15, could void car warranties on most cars. More corrosive than traditional gasoline, some studies show E15 may accelerate wear and tear on engines and components.

Federal agencies are pushing E15 as one component of a broader energy policy that promotes alternative fuels as a way to wean the country away from its reliance on foreign oil. The fiscal cliff bills extends a tax credit that makes it easier for gas stations to install E15 pumps and storage tanks. Experts say they think this will accelerate the arrival of E15 across the nation.

"Our concern is when you look through some of the research out there, you say, 'Boy, if this is half right, we should really be concerned,' " said John Nielsen, AAA's director of automotive engineering and repair.

Chrysler, Nissan, Toyota, Volkswagen and BMW have all stated their warranties do not cover damages related to use of E15. Eight other automakers tell AAA they may cancel warranty coverage, depending on what needs to be repaired.

The only auto manufacturers to specifically approve use of E15 are Porsche (on models built since 2001), and Ford and General Motors, which have approved its use on flex-fuel vehicles built in 2012 and 2013, respectively.

Last month, AAA asked the Environmental Protection Agency to suspend sales of E15, a blend of 15 percent ethanol and 85 percent traditional gasoline, until more tests can be conducted and consumers can be educated about the distinction between the different blends. But the federal government is speeding up, not slowing, down the introduction of E15.

AAA estimates that only 12 million of the nation's 240 million light-duty vehicles are equipped to handle E15, and that the danger of damage is especially higher in cars built in 2001 or earlier. Nielsen said the organization analyzed more than 30 research studies that ranged from emissions testing, engine testing and environmental impact before deciding to call for the suspension of its use.

"This has really percolated up as a subject, and we really believe there just needs to be more research on how E15 affects engines and components," Nielsen said. "With many car makers saying they won't honor warranties, this is a choice consumers have to make."

Much of the fuel sold in the United States is a blend of corn-based ethanol and gasoline. A 10 percent ethanol blend was the highest permitted by the Environmental Protection Agency until October 2010, when the agency authorized sales of E15 to cars or pickups built in 2007 or later. Soon after, the EPA expanded the waiver to include cars built from 2001 onward. (The waivers allow, but do not require, the sale of E15).

Whether drivers pay attention to such specifics when they pull into a gas station is a top concern for AAA. Ninety-five percent of drivers surveyed by the organization had no awareness of the fuel distinctions. But that lack of awareness could be because E15 is not widely sold beyond a handful of Midwestern states – yet.

Thanks to the tax credit extension – and a federal mandate that refiners blend 36 billion gallons of ethanol by 2022 – E15 is expected to soon reach more of the nation's 160,000 gas stations.

"The extension of these important provisions demonstrates the Obama administration's stalwart support of biofuels," Bob Dinneen, president and CEO of the Renewable Fuels Association told Biomass Magazine. "Equally significant is the extension of the alternative fuel tax credit, which will accelerate E15's entry into the marketplace this coming year."

Dinneen said E15 was the "most tested fuel" in the history of the EPA. In issuing its waivers, the agency said its decision was based on a conclusion that E15 would not cause or contribute to failures of emissions standards.

Studies on E15's harmfulness have shown conflicting results.

Critics have said the EPA only tested E15 for emissions standards - not engine wear - but the agency said it relied on testing conducted by the Department of Energy, which measured emissions, catalyst and engine durability, vehicle and engine components. A 2008 DOE test of 13 popular models concluded:

"Under normal operations, catalyst temperatures in the 13 cars were largely unchanged. When tested under full-throttle conditions, about half of the cars exhibited slightly increased catalyst temperatures with E15 and E20, compared to traditional gasoline."

An engineering analysis of E15 performed by Ricardo Inc. reached a similar finding, concluding that E15 should not hurt vehicles manufactured between 1994 and 2000, and those vehicles do not represent any obstacle in raising the blend limit. Yet a study done by the Coordinating Research Council in May of 2012 found E15 could harm car and light truck engines.

Determining which study among dozens to find credible can be difficult. The Ricardo study was conducted on behalf of the Renewable Fuels Association; the Coordinating Research Council study done for the American Petroleum Institute. Beyond the particular debate of whether E15 harms a car's engine is a broader one that involves considerable political jousting.

Poultry and cattle farm lobbies have opposed E15, because its production could increase the price of corn needed to feed their animals. Likewise, the oil industry has opposed it because E15 lessens the country's need for petroleum. The biofuels industry, on the other hand, believes that it supports corn farmers across the Midwest, as well as thousands of jobs in the fledgling alternative fuels industry.

"Ultimately, this is a fight about the next generation," Dinneen said. "The ethanol industry has become a tremendous success. We've become a victim of our own success, because we've awakened the oil companies."

Careful to avoid choosing a side in the political squabbling, Nielsen said there's wisdom in taking caution as that next generation of fuels approaches. Fearful potential complications have been overlooked, he says more testing of engines and other components should be done.

For example, part of EPA research found that 12 percent of vehicles tested on E15 had fuel-pump failures. "That's a reasonable outcome from increasing ethanol," he said, because traditional gasoline acts as a lubricant and ethanol does not. The EPA has called for increased testing on fuel pumps.

"It's an insidious problem," Nielsen said. "It's not a 'today' problem, but a long-term one. ... Cars could easily run for 200,000 miles, and if testing is saying there's wear occurring at 100,000 miles, that's a concern for most folks."


Tips for drivers

- Check your owner's manual to see if use of E15 is approved or mentioned. If you are unsure whether it's OK to use, check with your local dealership or automaker.

- Keep an eye on what you pump at the gas station. Currently, E15 is only available in a handful of Midwestern states. It's clearly marked at pumps where it is available.

- Don't panic. Even if E15 is not approved for your vehicle, experts say using it is more of a long-term problem. You won't damage your engine by using E15 in isolated instances. "Your car won't stall on the way home or anything," Nielsen said. "It's more of a buildup over time. If it's E15 or run out of gas, this isn't the end of the world."