Automobiles, also known as motor cars, are four-wheeled vehicles built for the transportation of passengers. Generally, they are powered by an internal-combustion engine that uses a volatile fuel for power. A modern automobile is a complex technological system with thousands of separate parts. Those parts are arranged into several semi-independent systems that have specific design functions.
One of the most significant inventions of the 20th century, the automobile has transformed our lives in ways that are hard to overstate. It allows us to travel to places we never could before and expands our work options, our social circles and where we can live in relation to our jobs.
An automobile has many problems, some of which are very serious. Accidents may be caused by human error, or the tires can lose contact with the road and cause a spin. Some engines are prone to overheating. The occupants of the car are vulnerable to smoke and fume inhalation and other harmful effects from air pollution.
The solution to these problems requires a great deal of research and development by engineers and scientists. Many of these improvements are costly, but there is a constant pressure to improve the quality and performance of automobiles. Improvements are made in the body, chassis, engine, transmission, drivetrain, braking and steering, control systems, safety systems and fuel economy.
The arrangement and choice of automobile components depend on the purpose and use of the vehicle. For example, a small car designed for city driving requires a smaller four-cylinder engine and has other design features that are different from a sports car designed for high speed and racing.