Gov. Terry Branstad joined six other Midwestern governors to send a letter to the U.S. Environmental Protection Agency asking for changes in a regulation they say is limiting the sales of E15 fuel. “EPA has the authority to resolve this regulatory hurdle to give more Americans the choice of a cleaner-burning, lower-cost, higher-octane, renewable fuel and we hope they do so immediately,” Branstad said in a statement. The regulation has to do with vapor pressure regulations, which vary between the more prevalent E10 mixtures and E15, which Branstad said is growing but held back by the differences in requirements. Read the letter here.