Automobiles are a complex technical system that includes thousands of subsystems with specific design functions. These systems depend on breakthroughs in existing technology and, as well, on many innovations that have evolved as a result of factors such as air pollution legislation, safety standards, competition among manufacturers worldwide, and technological advancements like electronic computers, high-strength plastics, and new alloys of steel and nonferrous metals. In a car, these systems control the body, chassis, engine, and drivetrain; provide a comfortable ride for passengers; facilitate steering and maneuvering; and deliver the power of the vehicle to the road.
The automobile has become one of the most important technological achievements of our time, and one of the greatest forces for change in twentieth-century America. It revolutionized personal mobility, giving people freedom of choice in where they work and live. It encouraged leisure activities, and with them new businesses and services. It has lowered the cost of living, expanded access to jobs and educational opportunities, and brought new conveniences like fast food restaurants and motels. It has also created new hazards, like traffic congestion and accidents, that have contributed to increased government regulation and safety requirements.
In the early twentieth century, automobile production was dominated by American companies that employed mass-production techniques pioneered by Henry Ford. These methods greatly reduced the price of cars, making them affordable to middle-class families. The automobile revolutionized the transportation industry, making possible a vast expansion of highways and cities and promoting the development of related industries, such as truck and bus manufacturing and gas stations. It has also brought new challenges, such as deteriorating engineering quality and environmental harm from excessive driving and the burning of fossil fuels.
Automobiles are powered by internal-combustion engines that burn gasoline or diesel fuel and are driven by front-wheel, rear-wheel, or four-wheel drive systems. The engine is usually carried in the front of the car, but can also be located in the rear or middle of the vehicle. The power of the engine is transferred to the wheels by a drive belt or chain. Some models have a liquid-cooled engine, while others have an air-cooled engine.
An automobile’s performance depends on the design, engine size, and type of fuel used. For example, a car built for off-road use must have durable, simple systems, while a vehicle designed for high-speed roads needs more passenger comfort options and optimized high-speed handling and stability. Safety features are an important feature of modern automobiles, and computerized safety systems have been developed that aid or even replace the driver in certain conditions.
The automobile is a significant contributor to air pollution, global climate change, and the depletion of natural resources like fossil fuels. Its exhaust fumes contribute to smog, while carbon dioxide and other greenhouse gases trap sunlight in the atmosphere, warming it. The automobile also contributes to noise pollution, traffic congestion and accidents, and is a major cause of injuries and fatalities on the road.