travel long distances at highway speeds using only the electricity generated instantaneously from the sun. Improving conventional cars A conventional vehicle can become a greener vehicle by mixing in renewable fuels or using less carbon intensive fossil fuel. Typical gasoline-powered cars can tolerate up to 10% ethanol. Brazil manufactured cars that run on neat ethanol, though there were discontinued. Another available option is a flexible-fuel vehicle which allows any blend of gasoline and ethanol, up to 85% in North America and Europe, and up to 100% in Brazil. Another existing option is to convert a conventional gasoline-powered to allow the alternative use of CNG. Pakistan, Argentina, Brazil, Iran, India, Italy, and China have the largest fleets of natural gas vehicles in the world. Diesel-powered vehicles can often transition completely to biodiesel, though the fuel is a very strong solvent, which can occasionally damage rubber seals in vehicles built before 1994. More commonly, however, biodiesel causes problems simply because it removes all of the built-up residue in an engine, clogging filters, unless care is taken when switching from dirty fossil-fuel derived diesel to bio-diesel. It is very effective at 'de-coking' the diesel engines combustion chambers and keeping them clean. Biodiesel is the lowest emission fuel available for diesel engines. Diesel engines are the most efficient car internal combustion engines. Biodiesel is the only fuel allowed in some North American national parks because spillages will completely bio-degrade within 21 days. Biodiesel and vegetable oil fuelled, diesel engined vehicles have been declared amongst the greenest in the US Tour de Sol competition. This presents problems, as biofuels can use food resources in order to provide mechanical energy for vehicles. Many experts point to this as a reason for growing food prices, particularly US Bio-ethanol fuel production which has affected maize prices. In order to have a low environmental impact, biofuels should be made only from waste products, or from new sources like algae. Electric Motor and Pedal Powered Vehicles Multiple companies are offering and developing two, three, and four wheel vehicles combining the characteristics of a bicycle with electric motors. US Federal, State and Local laws do not clearly nor consistently classify these vehicles as bicycles, electric bicycles, motorcycles, electric motorcycles, mopeds, Neighborhood Electric Vehicle, motorised quadricycle or as a car. Some laws have limits on top speeds, power of the motors, range, etc. while others do not. Other Public transportation vehicles are