Automobiles are modern, fast and versatile motor vehicles designed to transport people and things on land. They have four wheels, an internal combustion engine and are fueled most often by gasoline. The branches of engineering that study and produce automobiles are known as automotive engineering or automobile technology.
An automobile requires a number of systems to operate, such as cooling and lubrication systems, electrical systems, the engine and the chassis. These systems are arranged into semi-independent systems, much like the human body, and they are designed to interact with each other in ways that maximize performance and minimize noise and pollution.
The engine of an automobile uses gasoline, which has the advantage of providing a high level of performance for a relatively low cost. This advantage makes gas-powered automobiles the most popular form of vehicle in the world. However, other fuels are possible, including electricity and hydrogen. These alternatives offer greater energy density and higher speed performance, but they are not yet widely available.
Automobiles allow individuals to travel long distances quickly, changing lifestyles and economic patterns. Entire societies have been reorganized around the freedom of movement that these vehicles confer, and around the flexible distribution of goods made possible by trucks. At the same time, the environmental harm caused by automobiles — air pollution, destruction of landscapes and overdevelopment of undeveloped areas — is a major concern for many people.
Auto makers have fought back against criticism of their products by promoting safety features such as seat belts and air bags, and by arguing that improving roads, licensing drivers and regulating traffic are the keys to preventing accidents. They have also marketed the automobile as an expression of personal style and individuality. In 1916, Nell Richardson and Alice Burke drove across the country in an automobile decorated with banners that read “votes for women.”
Modern cars are built to take a fair amount of abuse, so they must be designed with a sturdy chassis and suspension system that can withstand repeated collisions. The chassis is the main structural component of an automobile, supporting the engine and most of the other systems. The suspension system consists of springs that absorb the shock from road surfaces and vibrations. These springs are supported by shock absorbers, which dampen or quiet the action of the springs using tubes and chambers filled with hydraulic fluid.
In addition to the safety systems, an automobile must have a steering and braking system, which are controlled by the driver. The body of an automobile, analogous to the skeletal structure in a human body, provides a protective covering and adds to the comfort and styling of the interior. The body must be constructed to meet certain standards for safety, size and weight, aerodynamics and the use of materials that are resistant to corrosion or rust. Other factors influencing the design of an automobile include the needs for passenger comfort and the requirements for pollution-control systems. Some of these factors have to do with how the body is designed and positioned on the chassis, while others have to do with the way the components are assembled into an integrated whole.