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An automobile (self-moving) is a wheeled, self-powered vehicle, meaning it carries its own engine. Automobiles are also called cars (from the word carriage). Most autos are designed to travel on roads built specially for them, although some, notably SUVs, are designed to be able to travel over primitive or non-existent roads.

The typical automobile has just an internal combustion engine and four wheels, although as of 2002 gas-electric hybrid engine powered cars have begun to enter the market. Three-wheeled automobiles have been built, but are not common due to stability problems.

Automobiles come in configurations such as

• sedan
• bubble car
• convertible
• station wagon
• sports coupe
• hatchback
• van
• minivan
• truck or lorry
• SUV (Sports Utility Vehicle)

The first automobiles were steam engine powered, then electric. Later on gasoline (petrol) and diesel engines were implemented.

While steam-powered vehicles were devised as the late 18th century, it is generally claimed that the first automobiles with an internal combustion engine were completed almost simultaneously in 1886 by two German inventors working independently, Gottlieb Daimler and Karl Benz. The large scale, production-line manufacturing of affordable automobiles was developed by Henry Ford in the 1910s. Early automobiles were often referred to as 'horseless carriages', which gives some idea of their design.

Alternative fuels for the gasoline (or petrol) engine have been around for many years. During World War II, coal gas was used. Methanol and ethanol (alcohols) are used as petrol extenders in some countries, notably in Queensland, Australia. Methanol is often used as a fuel for high performance racing cars.

In countries such as Italy and New Zealand, plentiful supplies of natural gas have seen methane sold as compressed natural gas (CNG) and butane sold as liquified petroleum gas (LPG) along side petrol and diesel fuels since the 1970s. While a standard automotive engine will run on these fuels, there is some performance differences, notably a loss of power, due to the slower combusion of the alternative fuels. The power loss can often be reduced or eliminated by retuning the engine ignition, or fitting an electronic dual fuel ignition system that compensates for the slower burning fuel. The need to equip filling stations and vehicles with pressure vessels to hold these gaseous fuels and the more stringent safety inspections means that they are only economical in high mileage vehicles or if there are installation incentives. They are most economical where petrol has high taxes and the alternative fuels do not.

The many varieties of automobile racing collectively constitute one of the most popular categories of sport in the world.

Major Possible Subsystems of a standard Automobile

• engine
  • fuel injection
  • engine configuration (V8, V6, V12, straight four, six, eights, flat-fours and sixes etc).
  • engine management systems
  • pollution control devices
  • exhaust system
  • turbo-chargers and superchargers
• drivetrain
  • gearbox (transmission)
  • differential
    • limited slip differential
• steering
• brakes
  • disc brakes
  • drum brakes
  • anti-lock braking systems (ABS)
• wheels and tires
• suspension
  • MacPherson strut
  • wishbone
  • multi-link
  • torsion beam
  • semi-trailing arm
• body
  • crumple zones
  • monocoque construction
• interior equipment
  • passive safety
    • seat belts
    • airbags
  • controls
  • seats
  • ancillary equipment such as stereos, air conditioning, cruise control, positioning systems, cup holders, etc.

Safety

Every year thousands of people are killed in traffic, often under the influence of alcohol, either by crashing into something, or by being crashed into. Special safety features have been built into cars for years:

• ABS, Anti-lock Braking System, which prevents the car from skidding
• Airbags, which inflate in a crash to cushion the blow of a head on the dashboard
• crumple zones, which buffers the impact when the car hits something
• safety belts, which keep a person from being thrown forward
• cage construction

Future

With heavy taxes on fuel, particularly in Europe, tightening environmental laws in the United States, particularly in California, and the possibility of further restrictions on greenhouse gas emissions, work on alternative power systems for vehicles continues. Attempts at building viable battery-powered electric vehicles continued throughout the 1990s (notably General Motors with the EV1), but cost, speed and inferior driving range made them unviable. Current research and development is centred on "hybrid" vehicles that use both electric and combustion power, and longer-term efforts are based around electric vehicles powered by fuel cells. Other alternatives being explored involve methane and hydrogen-burning vehicles, and even the stored energy of compressed air (see Air Engine).

See List of automobiles

See also two-stroke cycle, four-stroke cycle, diesel cycle, rotary engine (Wankel), urban car, flying car, armored car, road, traffic law.