Iowa Corn Growers are pushing a bill that gives gas stations an incentive to sell corn-based ethanol fuel. Tade Sullivan is director of public policy for the Corn Growers. He says studies show the incentives are the best way short of a mandate to promote ethanol consumption.Gas stations with ethanol sales that account for over 60 percent of their volume would get a state income tax credit. Sullivan says that incentive is the next best thing to a statewide mandate that stations sell only ethanol, as it takes advantage of the competitive nature of gas stations.The Corn Growers estimate ethanol usage would go up five to seven percent in the first year.The bill passed the Iowa House yesterday and is scheduled for debate in the Senate today. Fifty-three percent of the fuel sold in Iowa last month was ethanol.