The alternate fuels are substitute fuel sources to petroleum. These fuels are important because they replace petroleum fuels; however, some still include a small amount of petroleum in the mixture. Almost all motor vehicles today are powered by either diesel or gasoline. Both fuels are mainly derived from petroleum. Diesel fuel consists of hydrocarbons with between 9 and 27 carbon atoms in a chain as well as a smaller amount of sulfur, nitrogen, oxygen, and metal compounds. There are four alternate fuels that can be relatively easily used in conventional diesel engines: vegetable oil, biodiesel, Fischer-Tropsch (F-T), and dimethyl ether (DME). Gasoline is a blend of hydrocarbons with some contaminants, including sulfur, nitrogen, oxygen, and certain metals. The four major constituent groups of gasoline are olefins, aromatics, paraffins, and napthenes. The main alternate fuels include alcohol, liquefied petroleum gas, compressed natural gas, hydrogen, and electricity for operation of gasoline-type vehicles. Blended with petrol at 10%, bioethanol can be used in vehicles without the need to change fuel or engine specifications.