Automobile

      An automobile, autocar, motor car or car is a wheeled motor vehicle used for transportingpassengers, which also carries its own engine or motor. Most definitions of the term specify that automobiles are designed to run primarily on roads, to have seating for one to eight people, to typically have four wheels, and to be constructed principally for the transport of people rather than goods.

     The term motorcar has also been used in the context of electrified rail systems to denote a car which functions as a small locomotive but also provides space for passengers and baggage.

     These locomotive cars were often used on suburban routes by both interurban and intercity railroad systems.

     There are approximately 600 million passenger cars worldwide (roughly one car per eleven people). Around the world, there were about 806 million cars and light trucks on the road in 2007; they burn over a billion cubic meters (260 billion US gallons) of petrol/gasoline and diesel fuel yearly. The numbers are increasing rapidly, especially in China and India.

Etymology

      The word automobile comes, via the French automobile, from the Ancient Greek word αὐτός (autós, "self") and the Latin mobilis ("movable"); meaning a vehicle that moves itself, rather than being pulled or pushed by a separate animal or another vehicle. The alternative name car is believed to originate from the Latin word carrus or carrum ("wheeled vehicle"), or the Middle English word carre ("cart") (from Old North French), or from the Gaulish word karros (a GallicChariot).

Fuel and propulsion technologies

     Most automobiles in use today are propelled by a internal combustion engine, fueled bydeflagration of gasoline (also known as petrol) or diesel. Both fuels are known to cause air pollution and are also blamed for contributing to climate change and global warming.^[30] Rapidly increasing oil prices, concerns about oil dependence, tightening environmental laws and restrictions on greenhouse gas emissions are propelling work on alternative power systems for automobiles. Efforts to improve or replace existing technologies include the development of hybrid vehicles, plug-in electric vehicles and hydrogen vehicles. Vehicles using alternative fuels such asethanol flexible-fuel vehicles and natural gas vehicles are also gaining popularity in some countries.