Automobiles are vehicles that carry passengers and cargo over roads and highways. Almost all automobiles use an internal combustion engine that burns fuel to generate power and drive the car. The modern automobile contains many complex systems that work together to provide power, control, and comfort.
An automobile can be powered by gasoline, diesel, natural gas, liquefied petroleum gases (LPG), or electricity. Several types of transmission systems are used to deliver torque from the engine to the wheels. Modern automobiles also include control systems, electrical equipment, and service devices.
Among the most significant inventions of modern times, the automobile has had a profound impact on human society and the economy. It is difficult to imagine a world without cars, as they are a common mode of transportation for people and goods. In the United States, people drive more than three trillion kilometers (five billion miles) each year.
Although millions of people around the world depend on their cars for transport, they can cause problems if too many cars are driving at the same time. Traffic congestion slows the movement of cars, and air pollution from automobile exhaust contributes to climate change. However, automobiles also create jobs by providing jobs at factories that make them and at places where travelers stop to buy fuel or food. People who design and maintain automobiles need to take all these factors into account when planning their designs. They must balance performance, safety, cost, and aesthetics.