Automobiles, also called motorcars or cars, are four-wheeled vehicles that use an internal combustion engine to propel themselves. They run primarily on roads, seat one to eight people and transport passengers rather than cargo. The modern automobile is a complex technical system whose subsystems perform specific design functions. Its development has been shaped by advances in technology and changes in social and economic conditions.

The automobile has become the dominant form of transportation in the world, and it plays a critical role in the economy of many nations. It has helped create new jobs and industries, such as oil refining and car manufacturing, and it has radically changed the way we live and work. But the automobile has also brought some problems, such as air pollution and traffic congestion. It has also contributed to the loss of undeveloped land for highways and parking lots.

A modern automobile has a number of different components, including the frame, suspension and wheels. The design of each of these parts depends on the type of car, the driving conditions and the performance goals. For example, a vehicle that is designed for off-road use requires durable and simple systems that are easy to maintain. It must also be able to withstand severe overloads and extreme operating conditions. On the other hand, vehicles designed for high-speed road systems require passenger comfort options, optimized engine performance and improved handling and stability.

The modern automobile is powered by an internal combustion engine that burns gasoline or diesel fuel. Its design has been influenced by technological advancements, such as electronic computers and advanced alloys of steel and nonferrous metals. The automotive industry has revolutionized industrial production through the use of assembly lines and other mass-production techniques.

The scientific and technical building blocks of the automobile date back several hundred years, but it was not until the late 1800s that major improvements were made in both the engineering and mechanical aspects of the vehicles. Early automobiles were powered by steam, electric power or a mixture of steam and gasoline. Although they could reach high speeds, these vehicles were difficult to start and required frequent stops for refueling. Eventually, manufacturers chose to use gasoline engines, which were more powerful and easier to operate. In addition, they were able to travel longer distances than the battery-powered or steam-powered automobiles. The automobile is a symbol of freedom and the American dream. Its development has been linked to the rise of a consumer society and has become one of the most important forces for change in twentieth-century America. However, the era of the automobile is fading as other forces chart the future of the nation.