When Bruce Jones and his colleagues began a study on how higher blends of ethanol would affect gas mileage, he expected to prove conventional wisdom true: The more ethanol added to gasoline, the lower the gas mileage.

But when using a 20 to 30 percent blend, not only didn’t mileage drop compared to pure gasoline, it offered the same to slightly better fuel efficiency.

“It’s definitely more efficient than we had estimated.”

Jones is director of the Minnesota Center for Automotive Research — MnCAR — based at Minnesota State University.

Jones warns the study was small — using only four vehicles — and upcoming broader research by others will need to be evaluated to see if the results hold true.

MnCAR used four 2007 vehicles: a Toyota Camry, Ford Fusion and two Chevrolet Impalas. One of the vehicles was a “flex-fuel” car designed to burn up to 85 percent ethanol, the other three were standard gasoline engines.

If the research holds up, it could significantly change the view of ethanol blends. Because ethanol contains less energy, it generally produces a lower gas mileage.

Jones said they do know that E85 — 85 percent ethanol — does reduce gas mileage. But he said there appears to be a certain mixture — above the standard 10 percent but less than 30 percent — in which the mix about equals the fuel efficiency of pure gasoline.

“There’s something going on there we don’t entirely understand,” he said.

But he has an idea. Many newer vehicles have an automatic calibration mechanism that advances ignition timing as octane levels in the fuel increase. Ethanol does have high octane. Jones thinks hitting just the right mix of ethanol, gas and octane may maximize the ignition timing on the cars.

“This is a small, small sample. This shouldn’t be perceived as the definite answer. You’ll have to look at a lot more vehicles to find if it’s definitely better than gasoline.”

The MnCAR study was part of a broader study done by the University of North Dakota Energy & Environment Research Center.

He said the Department of Agriculture is to release results of a similar larger study later this month.

MnCAR began in the mid 1990s but has received more attention and grants in recent years as the state and biofuels industries have looked to it for research. The state had turned to MnCAR to study ethanol after Gov. Tim Pawlenty made the push to have all fuel in the state contain at least 20 percent ethanol by the year 2012.

Jones said getting to that level could come from either a mix of traditional 10 percent ethanol and E85 ethanol, or by a blend somewhere in between.