An automobile is a four-wheeled motor vehicle designed for passenger transportation and powered by an internal combustion engine using a volatile fuel. Modern automobiles are built with several structural and mechanical systems, including the body (containing passengers, storage, and control systems), chassis, or steel frame; the internal combustion gasoline or electric motor; the drivetrain; the steering system; the brakes; and the electrical and power generation and distribution systems. These systems work together to create a safe and convenient means of transportation, providing the freedom and flexibility to travel to and from destinations on one’s own schedule without having to wait for or transfer between public transportation services.

Automobiles are widely used around the world for travel and trade, serving as the primary means of personal transport in most countries. They are a key force in modern society, the backbone of a consumer goods-oriented economy, and the largest consumers of petroleum, iron and steel, rubber, and other industrial products. They also contribute to air pollution, and have been linked to climate change. In addition, they can be a source of conflict over access to public space and resources, such as parking.

The development of the automobile, beginning in the late 19th century, transformed American life and culture. It created a middle class with the means to purchase automobiles, opening up a new realm of social and leisure activities for them. Automobiles enabled them to visit places that were previously unavailable, such as rural areas or locations served by limited public transportation services.

As the industry became more consolidated in the 1920s, it grew to dominate the economy and provided employment opportunities in many different fields. By 1982, it ranked first in value of product and provided one out of six jobs in the nation. The automobile was the lifeblood of the petroleum industry, the biggest customer of steel and a major consumer of other industrial products. Its demand revolutionized the technology of ancillary industries.

In the early 20th century, automobile companies began to specialize in particular models. European manufacturers tended to be more self-sufficient, but the great majority of the United States producers were assemblers, selling finished cars that included components manufactured by other firms. This assembly technique reduced the cost of production and allowed automobiles to be priced within the reach of most middle-class Americans. Among the earliest of these vehicles was the 1901 Mercedes, an advanced design with a luxurious interior that contrasted with Ransom E. Olds’ tiller-steered, curved-dash one-cylinder, three-horsepower Oldsmobile, which sold for $650.