Automobiles are wheeled vehicles that primarily transport passengers rather than cargo. Most modern automobiles are powered by a liquid-cooled, piston-type internal combustion engine that may be mounted to drive one or more wheels (or all four) directly or to power other mechanical systems. Some automobiles use air-cooled engines, which are less efficient but generally simpler and more compact. The engine may be mounted on the front of the car, on the rear, or between two axles; the latter configuration is more space-efficient but may compromise stability and handling. Various fuel sources are used, including gasoline and petroleum-derived synthetic or “fossil” fuels. A large number of different body styles and sizes are produced, ranging from small two-door economy cars to luxury sports utility vehicles.

The development of the automobile is often considered to be a major turning point in modern history. It revolutionized transportation, created jobs in factories and service stations, and led to development of better roads.

Unlike trains or ships, airplanes, or even horses, the automobile allows its passengers to travel over long distances quickly and conveniently, while remaining comparatively stable, able to turn sharply, and offering comfort and flexibility not available before. While the automobile has not been universally adopted, it has been a significant force for change in twentieth-century society.

Most of the early motor vehicles were steam or electrically powered, but it was not until Ransom E. Olds’ 1901-1906 one-cylinder, three-horsepower, tiller-steered, curved-dash Oldsmobile that an affordable automobile became a reality. Ford developed modern mass production techniques at his Highland Park, Michigan, plant, allowing the Model T to be manufactured at a price that placed it within the range of middle-class Americans.

While the automobile has become a vital force in our economy, it has also been a source of social problems such as pollution and congestion. Some experts argue that the automobile has shifted social capital away from more productive activities and toward recreational pursuits, but others maintain that it has provided many householders with access to work and social opportunities that would not otherwise be available.

As automobiles have improved, they have also become more expensive and many households cannot afford to own them. While the automobile has become a fixture of American life, it is now being replaced as a progressive force by other technological advancements such as the personal computer.

Today’s cars are designed with a wide variety of safety features such as seat belts, airbags, and antilock brakes. Passenger comfort options include reclining seats and climate control. Stability and handling are optimized by a combination of factors, including the placement of the engine in relation to the chassis and weight distribution, the type of tire and tread pattern, suspension characteristics, and steering system. Increasingly, automobiles are incorporating electronic components such as the microprocessor and the laser. These are often integrated into the navigation, entertainment, and communications systems of the vehicle. These technologies are allowing for new, safer, more energy-efficient, and environmentally friendly vehicles to be designed.