Automobiles are powered by internal combustion engines and fueled most often by gasoline, a liquid petroleum product. They are the dominant mode of land transportation and a major contributor to air pollution worldwide. In the United States, automobiles are manufactured in large quantities by Ford, General Motors and Chrysler, which together comprise a global industry known as the Big Three. The invention of the automobile is one of the most significant milestones in modern civilization. It has fundamentally altered human lifestyles by making it possible for people to travel longer distances more rapidly than ever before, thus increasing freedom and expanding opportunities. It is also a vital component of the economy, both as a form of retail commerce and for transporting raw materials to manufacture other goods.
The automobile has evolved dramatically since the early 1900s. In the first half of that century, American manufacturers revolutionized industrial manufacturing through the introduction of assembly lines. This greatly increased production efficiency and brought the price of a car down to a level affordable by most middle-class Americans. The car became a fixture in the social landscape, encouraging families to vacation away from urban centers and providing teenagers with the opportunity for more personal independence and mobility. It spawned new social habits, including relaxed sexual attitudes and a greater number of marriages between heterosexual couples. It also led to the development of traffic congestion and safety laws.
The design of a car depends to a large extent on the vehicle’s intended use. Products for off-road or other rough conditions require durable and simple systems that have high resistance to severe overloads. Cars that will be used on limited-access highway systems must be optimized for passenger comfort and high-speed handling. They must have good fuel economy and safety features, and the engine must be designed for reliability under these operating conditions.
As a result of technical advancements, many automobiles now have multiple drivetrains and various systems for improving passenger comfort and handling. They are equipped with electronic devices, telematics systems and advanced safety and security technologies. They can be powered by internal combustion, electric motors or by a combination of both.
Automobiles are subject to a wide variety of environmental, economic and geopolitical influences. They use a substantial amount of raw material resources such as metals, rubber, plastics, glass and oil, which are sourced from all over the world. Changing supply and demand factors may affect the prices of these commodities, as well as the availability of skilled labor and energy required to produce cars. For these reasons, automobile production is a sensitive economic and geopolitical issue.