Toyota Prius, a hybrid vehicle. Museum of Toyota of Aichi Prefecture, Japan. An alternative fuel vehicle is a vehicle that runs on a fuel other than "traditional" petroleum fuels (petrol or diesel); any method of powering an engine that does not involve solely petroleum (e.g. electric car, petrol-electric hybrid, solar powered). Due to a combination of heavy taxes on fuel, particularly in Europe; tightening environmental laws, particularly in California; the potential for peak oil, and the possibility of further restrictions on greenhouse gas emissions, work on alternative power systems for vehicles has become a high priority for governments and vehicle manufacturers around the world. "Hybrid" vehicles such as the Toyota Prius are not, of themselves, alternative fuel vehicles - clever use of a battery, motor/generator, merely means that a more efficient but less powerful engine can be used. Essentially all the power comes from petroleum [1]. The first hybrid vehicle available for sale in the United States was the Honda Insight, achieving around 70 miles per gallon (3.4 liters per 100 km). Other research and development efforts in alternative forms of power focus on developing fuel cells, alternative forms of combustion such as GDI and HCCI, and even the stored energy of compressed air (see Air Engine). Greasestock is an event held yearly in Yorktown Heights, New York, and is one of the largest showcases of alternative fuel vehicles in the United States.[2][3][4][5][6][7] Contents 1 Single fuel source 1.1 Air Engine car 1.2 Battery-electric 1.2.1 Solar 1.3 Ammonia fueled vehicles 1.4 Biofuels 1.4.1 Bioalcohol / Ethanol 1.4.2 Biodiesel 1.4.3 Biogas 1.5 CNG Compressed Natural Gas 1.6 Hydrogen 1.7 Liquid nitrogen car 1.8 LPG or Autogas 1.9 Propane 1.10 Steam 1.11 Wood gas 1.12 Gasoline Vapor 2 Multiple fuel source 2.1 Flexible fuel 2.2 Hybrid 2.2.1 Pedal-assisted electric hybrid vehicle 3