Automobiles are powered by engines or motors that convert chemical energy into mechanical energy. They transfer that energy through axles that drive wheels to move the vehicle on land, and via paddle wheeled propulsion in water. Today, the world’s 1.4 billion cars and trucks cover trillions of miles each year. They transport people and goods, connect cities and suburbs, and are the principal means of transportation in many countries.
Most cars have an engine, transmission, chassis, bodywork, control system, electrical equipment, service devices, and other components. The engine can be gasoline (carburetor internal combustion), diesel, natural gas, or electric. A car needs a large amount of fuel to run, which is usually oil extracted from the ground. The oil is refined to make gasoline or diesel, and it is burned in the engine to produce mechanical energy that moves the wheels. The power of the engine is measured by its rated horsepower or kilowatts.
The first automobiles were powered by steam or electricity. Nicolas-Joseph Cugnot built a three-wheel steam-powered vehicle in 1769. Oliver Evans of Pennsylvania obtained the first U.S. patent for a self-propelled vehicle in 1804; his invention was essentially a harbor dredge scow that could travel on wheels on land and through paddlewheels on water. The modern automobile was perfected in Germany and France toward the end of the 1800s by inventors such as Gottlieb Daimler, Karl Benz, Nicolaus Otto, and Emile Levassor. The 1901 Mercedes, designed by Wilhelm Maybach for the Daimler Motoren Gesellschaft, is considered the first true modern motorcar in every respect.
During the early 1900s, American manufacturers pioneered production line manufacturing techniques to mass-produce inexpensive cars that were affordable for middle-class consumers. This was a huge step forward, as it gave rise to the modern highway network and related infrastructure. It also fueled the predilection of Americans for freedom of movement and action, which eventually led to suburbanization and large-scale family-centered communities.
While the automobile has transformed many aspects of human life, its environmental impact is a serious problem. Automobiles pollute the environment through exhaust and emissions, degrade soil and water quality, and consume a large quantity of energy. They also contribute to climate change, since fossil fuels are major greenhouse gases.
Despite these problems, the automobile is still an important mode of transportation in many parts of the world. The automobile continues to evolve as manufacturers develop more efficient engines, improve safety features, and offer a variety of new functions, including satellite navigation and GPS systems, advanced electronics, and hybrid propulsion. The world’s car industry is booming, with annual sales of vehicles exceeding five trillion dollars in 2009. China and the United States are the leading auto markets. The term automobile is also used as a generic name for any road-going motor vehicle, regardless of its type or design. See also: bus; taxicab; truck; automobile accident; automotive manufacturer; motorcycle; refuel; automobile; automobile magazine; car dealer; ethanol; hydrogen fuel cell; rotary engine.