Some automobiles burn diesel fuel, which is used in big trucks and buses, and a few use wood gas. In some countries, such as Brazil and Sweden, a mixture of ethanol and gasoline, called ""gasohol"" in Brazil and ""E85"" in Sweden, is used as automobile fuel. Other fuels include propane, natural gas, compressed air, and ethanol (which comes from plants). There are automobiles designed to run on more than one type of fuel — these are called ""flex-fuel"" and are rare.