An automobile, formerly called a motorcar or a carriage, is a self-propelled vehicle used for passenger transportation and powered by an internal combustion engine using fuel. Modern automobiles are complex technical systems employing thousands of subsystems with specific design functions. These subsystems are the product of breakthroughs in several fields including electronic computers, high-strength plastics and new alloys of steel and nonferrous metals.

The automobile has revolutionized modern life by making it possible to travel long distances at a reasonable speed in comfort and safety. It has reduced commuting times and allowed people to spend more time with family and friends, while making business trips more productive. It has also stimulated travel and tourism industries, contributed to suburbanization and helped create rural services such as gas stations, roadside restaurants and hotels. It has also led to the development of public roads and highways, one of the largest items of government spending.

Exactly who invented the automobile is a subject of some controversy. It is generally agreed that Carl Benz, from Germany, and Henry Ford, from the United States, each made significant contributions in the early years of the 20th century. Ford was responsible for mass production of the Model T, which brought automobiles within reach of middle-class families. He introduced innovative manufacturing techniques, such as the moving assembly line. Benz was responsible for the invention of the four-cylinder, gasoline-powered car engine.

Automobiles have evolved to include an extensive array of models with different sizes, capabilities and appearances. Most of these are powered by internal combustion engines, fueled most often by gasoline (but sometimes by diesel fuel or kerosene). Some are electrically powered, and a few run on alternative fuels such as batteries or liquefied petroleum gas.

Some of the most popular automobiles are sports cars, which are designed for speed and performance. These cars have a powerful engine, fast gearbox and tight handling. Some are built for luxury and comfort, with amenities such as air conditioning and leather seats. Other popular vehicles are crossover SUVs, which combine the towing capability of a pickup truck with the cargo space of a station wagon or passenger van.

The era of the annually restyled “road cruiser” ended with the imposition of federal standards for automotive safety, pollution and energy consumption; with escalating gasoline prices following the oil shocks of 1973 and 1979; and with the penetration of the American and world markets first by the German Volkswagen “Bug” and then by Japanese fuel-efficient, functionally designed, well-built small cars. These developments reflected the reality that higher unit profits for Detroit manufacturers on the sale of gas-guzzling, low-quality, large automobiles came at the social cost of increased air pollution and a drain on dwindling world oil supplies.