Automobiles are four-wheeled motor vehicles used mainly for passenger transportation and powered by an internal combustion engine that burns liquid petroleum fuel. They are one of the most universal of modern technologies, and they comprise thousands of components that have been developed by research and development engineers and manufacturers in accordance with specific design functions. The automobile industry, sometimes called the auto industry or car industry, is one of the largest industries in the world.
The automobile revolutionized everyday life in America and around the world. It brought freedom and mobility for many people that had never before experienced it. It created new jobs and industries, such as the manufacture of cars, tires and other vehicle parts. It also led to the creation of services such as gas stations and convenience stores.
There have been many different designs of automobiles, but the majority use an internal combustion engine to power the wheels. The fuel, usually gasoline but sometimes diesel or kerosene, is injected into the engine where it is burned. The resulting hot gases push down on the pistons, which then turn the wheels of the automobile. The wheels are connected to the crankshaft by means of a differential and axles.
A key part of the modern automobile is its engine, which must be designed to perform well under a wide variety of conditions and circumstances. The engine is a complex arrangement of many subsystems, including an intake system that draws in air and fuel from the environment; a compression system that raises and lowers the pressure within each cylinder; a combustion process that transforms the fuel into energy to move the car; and a valve train that controls and monitors the engine function.
Other parts of the automobile are less visible but equally important. For example, the chassis is a framework that holds the body and engine. Its strength, stability and handling are essential for safety. It must be strong enough to absorb the shocks and vibrations of driving on rough roads. It must also support the weight of the engine, passengers and cargo.
The development of the modern automobile has been a long and arduous process. Some of the early automobiles were steam-powered, but it was Karl Benz who first designed a practical internal combustion engine in 1886 that would propel his Benz Patent-Motorwagen. Ford introduced mass production with the Model T, which reduced costs to a point where middle-class Americans could afford it. But, by the beginning of the 21st century, American auto manufacturers were facing market saturation, and their sales had fallen off significantly. To maintain their sales, they introduced a wide range of models and features each year to attract new buyers.