Wally Lutz believes in ethanol, not least because his western Minnesota neighbors grow the corn that goes into the biofuel.

So for three years, Lutz has done his best to put at least half ethanol in his family cars, which aren't meant to be powered by anything but standard gasoline. His commitment meant a stop at a gasoline pump and another at an ethanol pump at his Montevideo Cenex station every time he fueled up.

Managers there noticed a lot of people doing the same, so in March they installed two "blender pumps" that mechanically do the mixing for their customers.

But Lutz -- and certainly many of the other Cenex customers -- are not driving cars with "flex-fuel" engines designed to burn a mixture that's mostly ethanol. And that makes them part of an open secret across Minnesota and much of the Upper Midwest: Growing numbers of drivers are choosing to burn the new fuel in their old cars.

They're taking some risk. They're violating federal clean air law, which forbids anything that compromises a vehicle's emission control system, according to the U.S. Environmental Protection Agency (EPA). They're also voiding manufacturer warranties; carmakers say the more-caustic ethanol damages the fuel systems in old cars.

"That's clear in our owners' manuals," said Kristen Kinley, a Ford Motor Co. spokeswoman.

But as gasoline prices teeter around $4 a gallon, car owners are looking for savings, and ethanol usually is priced 40 to 60 cents a gallon cheaper because of a federal subsidy. And while ethanol is blamed, in part, for higher grocery prices and increasing concern about global hunger, those drivers have chosen different ethanol politics. Ethanol helps liberate the country from foreign oil, and it burns cleaner than gasoline.

"The carmakers may be worried about it, but I'm not," said Lutz, 77, a retired gas-station operator. "And every gallon of ethanol just makes me feel good that it's not a gallon of imported oil."

Montevideo Cenex credit manager Robin Enevoldsen agreed: "We're just keepin' it local."

The burning question

In Minnesota, all regular unleaded gas already has 10 percent ethanol -- what's called an e10 blend -- and regular, gasoline-engine cars are not supposed to burn any other blend. Flex-fuel cars and trucks can burn anything up to e85, the highest blend on the market.

Officially, blender pumps -- which offer e20, e30, e50 and e85 mixes -- are intended to give flex-fuel vehicle owners more options. They can calibrate the best blend for their particular vehicles and driving habits -- balancing ethanol's lower price against a drop in fuel economy of as much as 25 percent.

And the pumps are serving that purpose, said Steve Kleespies, service manager at Westmor Industries in Morris, the region's largest blender-pump installer. Kleespies uses one to buy e50 for his 2006 Chevy Avalanche because it's cheaper than gasoline but delivers the same 19 miles per gallon, unlike e85.

But plenty of other drivers also are using the pumps, which have proliferated across Minnesota since the first one in Ortonville last fall. The Minnesota Department of Commerce counts 10 in the state, but Kleespies estimates there are up to 40 in operation or in planning. And they're popular once they're in. At two-day open houses in April, two Cenex stations in Montevideo and Granite Falls sold 1,000 gallons of e50 and nearly 5,000 gallons of e30, according to Enevoldsen.

AAA advises against

Many organizations advise against anything above e10 for cars lacking flex-fuel engines. AAA of Minnesota and Iowa disapproves. General Motors, like Ford, said anything above that voids a car's warranty. Even two pro-ethanol groups, the South Dakota-based American Coalition for Ethanol and the National Ethanol Vehicle Coalition in Missouri, said they don't recommend it.

But some research is encouraging such blends. Three studies so far that tested higher ethanol blends in gasoline-burning cars are considered too small to be definitive. But their results showed all emissions below the federal limits, mileage often comparable to gasoline and no fuel system or driveability problems, according to Bruce Jones, director of the Minnesota Center for Automotive Research at Minnesota State University Mankato. Enevoldsen said her two cars get better mileage with e20 than with gasoline.

Resolving compatibility questions for gasoline-burning vehicles soon will become even more important, because ethanol blends are expected to get richer. Minnesota has pledged to raise its regular gas to e20 by 2013, if the EPA grants a necessary waiver. And a new federal mandate to ramp up national ethanol use to 36 billion gallons by 2022 -- up from about 9 billion this year -- "means mid-level blends like e30 and e50 will likely have a bigger place in the fuel market," said Brian Jennings, executive vice president at the American Coalition for Ethanol.

Ford will address the implications of any such changes as they develop, Kinley said. "The best way to get there [more ethanol use], in GM's opinion, is to sell more flex-fuel vehicles," said spokesman Alan Adler.

No charges

The EPA said "misfueling" a car violates the U.S. Clean Air Act and carries a fine of up to $2,750 for the person doing the misfueling and possibly for the station owner. But a spokeswoman also said she could find no instance when the agency pressed a case. Enevoldsen said her stations are self-service, so it's the car owners, not her employees, who actually pump the ethanol into their fuel tanks.

At Westmor Industries, Kleespies said the blender pumps are clearly marked for flex-fuel vehicles only, "and everybody knows the station owners cannot police what fuels everybody is putting in their cars."

Even Donald Brown, who travels across Minnesota encouraging drivers to burn more ethanol, isn't worried the EPA will knock on his door. Brown, a retired truck driver, goes to gas stations that sell ethanol, and offers a $1 bill to anyone who will try it. Now 78 and living in Golden Valley, he says he's on a mission to improve the future for generations to come.

"We've got to get away from oil," he said. "It's killing our economy."

H.J. Cummins • 612-673-4671