Both AOPA and EAA are lobbying Congress to exempt aviation gasoline from two proposed amendments to the Clean Air Act. The bills propose making it mandatory for all motor vehicle gasolines (with a few exceptions for collector cars) to contain at least 10 percent "renewable fuels" by 2010. About the only viable alternative fuel now available is ethanol fermented from corn and it gives airplanes a major hangover. Separate studies by EAA, the FAA and Cessna have conclusively determined that ethanol damages everything from engines to fuel systems in airplanes, but the bills, as they stand now, would require the 10 percent quota for avgas. The groups are also hoping to get some relief for those with mogas STCs. In addition to exempting avgas, the groups want Congress to allow premium automotive fuel to be made without ethanol. The addition of ethanol invalidates the mogas STCs. Several states have seen the wisdom of having some alcohol-free fuel available, not only for airplanes but for boats and recreational products, and have exempted premium fuel from their own 10-percent rules.