The automobile is the means of transportation for most Americans. It has become a major factor in the economy, allowing people to work outside their homes and live in places where jobs are available. It also provides access to recreational activities and social services. Its use has brought new laws and government requirements such as seatbelts and highway rules. But it has also caused environmental problems such as air pollution and a drain on dwindling world oil reserves.

The modern automobile is a complex technical system with many subsystems that have specific design functions. Automobile engineering is the branch of engineering concerned with the manufacture and technology of motor vehicles. The modern automobile is propelled by an internal combustion engine using a volatile fuel. It is designed primarily for passenger transportation, but some models are used as freight transport and for police or military purposes.

Automobiles are a major part of the modern world, and life would be nearly inconceivable without them. There are more than 1.4 billion cars on the road today, and they travel three trillion miles (five trillion kilometers) a year in the United States alone. Cars can now be made from a wide variety of materials, including plastics and high-strength steel alloys. There are even hybrid and electric versions that combine the best features of a gasoline-powered vehicle with the alternative energy benefits of a battery-powered one.

The first modern automobiles were perfected in Germany and France in the late nineteenth century by such men as Gottlieb Daimler, Karl Benz, Nicolaus Otto, and Emile Levassor. They were expensive and polluting, but they offered the advantage of independence from horses.

Postwar production methods revolutionized automotive engineering. Henry Ford used assembly lines to mass-produce his Model T, lowering the price so that it could be affordable for middle class families. Other manufacturers followed suit. They created a wide variety of models with different specifications, but each one shared the same basic body structure. This enabled them to produce them at lower cost, and it made competition fierce.

In the 1960s questions began to arise about the nonfunctional styling of some American cars and about their safety and economic aspects, such as the higher unit profits Detroit made on gas guzzling “road cruisers” and their effect on dwindling world oil supplies. This opened the market to foreign manufacturers of functionally designed, well-built small cars that were efficient and affordable.

Since the 1930s, automobile design and production have increasingly merged with marketing plans. During the 1950s, Alfred P. Sloan established the concept of divisions within his General Motors Company to offer buyers a choice of makes according to their budgets, and the sharing of parts among different models allowed manufacturers to keep their costs down. This period has been called the Golden Age of the Automobile, but it is now a transitional era. New forces are changing the direction of the world’s economy and changing the way people get around.