Reuters: The U.S. Environmental Protection Agency said on Wednesday it will take another year to complete government testing on whether higher levels of ethanol can be blended into gasoline without harming engines. Ethanol is now approved to make up 10 percent of gasoline in cars and trucks. Producers are pushing the government to allow higher ethanol blend levels, as more ethanol will be required each year under federal law. Congress required 9 billion gallons of ethanol and other …