The automobile, also known as a car, is a four-wheeled passenger vehicle that is propelled by an internal combustion engine that burns a volatile fuel. It has become one of the most widely used forms of land transportation. Automobiles have transformed society by providing greater mobility and spawning new industries, such as manufacturing, retail and service. They are arguably the most important invention of the 20th century and have brought dramatic changes to industry and technology, everyday life, and social structure in the United States.

The modern automobile is a complex technical system with many subsystems that have specific design functions, such as safety, fuel efficiency, power and speed control, and suspension. The automotive industry is a global enterprise that requires heavy investment of capital and a large volume of production. It is dominated by American manufacturers Ford, General Motors and Chrysler, which make up the Big Three.

Automobiles were invented in the late 1800s and perfected in Germany and France by engineers such as Gottlieb Daimler, Karl Benz, Nicolaus Otto and Emile Levassor. However, it was American businessman Henry Ford who revolutionized the industry by innovating mass production techniques that made gasoline-powered cars affordable to middle class families. By 1920, the automobile had overtaken the streets and byways of the world.

With their capacity for carrying passengers and luggage, vehicles such as sedans and station wagons were able to greatly reduce the time people had to spend on transport and thus changed their lifestyles in unprecedented ways. Families now had the freedom to leave their homes whenever they wanted and to travel long distances, without having to wait for schedules of public transportation or worry about coordinating a ride through friends.

In addition, the advent of automobiles spawned new industries to provide the raw materials and services needed for their production and use. New jobs arose in manufacturing and supplying parts, such as tires and oil. Services, such as gas stations and convenience stores, also developed. The automobile also facilitated the growth of urban centers and created new leisure activities, such as amusement parks, restaurants, hotels and fast food chains.

Ultimately, the automobile became an integral part of American culture. Postwar into the 1960s, however, issues arose that questioned the nonfunctional styling of American manufactured automobiles and their impact on quality, economy, safety and environment. Concerns were also raised about the draining of dwindling world oil reserves.

Market saturation occurred simultaneously with technological stagnation and as a result, innovation in the industry slowed to a crawl, although some improvements were made. In the 1970s and 1980s, new innovations included improved electronic systems, safety features, increased engine performance and optimized high-speed handling. Today, SUVs and crossover vehicles offer a combination of sedan-like driving dynamics with off-road capability and cargo space, while small cars such as the Honda Civic and Toyota Corolla offer improved fuel economy over older models.