There's been a lot of concern expressed over the potentially damaging impact on engines that E15 – gasoline with 15 percent ethanol – could have on vehicle engines. AAA most recently sounded an alarm on the issue – the organization says that sale of E15 gasoline should be postponed until consumers can be educated on the fuel – and using the fuel can void the warranty in some vehicles.

Right now, drivers have access to E15 only in certain areas of the country, like Kansas and Iowa. To educate Eastern Iowan readers on what it costs to use E15 in their gas tanks, a local newspaper took a field trip to find out how the biofuel compares to fueling up on gasoline with E10. They accessed the Linn Co-op Oil Co. in Marion, IA, three times in the last month and found that on the first day, the E15 price was two cents per gallon more than E10 at nearby stations, and that it was approximately the same price for E10 at nearby stations on the two December dates.

The fuel economy experience was similar to typical gasoline with E10, even though higher ethanol concentrations in gasoline can be associated with a loss in fuel economy. The team tested E15 in a 2003 Volkswagen Golf with a 2.0 liter, four-cylinder engine with a typical mileage range of 28 to 32 miles per gallon, depending on driving conditions. Their experience was very similar with E15 – 31.5 mpg on the first fill-up and 28.6 mpg on the second.

Engine performance didn't appear to be impaired during the non-scientific test, and the risk of motorists accidentally filling the gas tank with E15 didn't seem to be a real problem. Pricing did seem to slightly favor E10 over E15, and having very limited access to E15 at gas pumps gives E10 the edge for now.

Granted, this is a very limited test run for E15, fitting since we're a long way away from the fuel being available at most gas stations across the country. For that to happen, it will take lots of user experiences similar to that experienced by the reporters – positive real world driving conditions and beneficial cent-to-cent comparisons. The numbers could be huge: the Iowa Renewable Fuels Association has calculated that drivers in Iowa could have saved $69 million this year had E15 been widely available. IRFA executive director Monte Shaw told Domestic Fuel, "Until E15 is widely available, Iowans will continue paying more at the pump than they should."