Automobiles, also called motor cars, are self-propelled vehicles for transporting passengers on paved roads. Automobiles are most often powered by internal combustion engines using volatile inflammable fuels such as gasoline (petrol), diesel, or kerosene, but they can also be driven by electric motors or by other sources of electrical energy, including regenerative braking that turns some of the car’s motion into electricity. They typically have four wheels and can range in size from small economy cars to large sports or luxury models.
Many factors affect automobile design. For example, the choice of front- or rear-wheel drive influences handling and stability. The layout of the engine and other automobile systems may depend on whether the vehicle is designed to be used off-road, which requires durable systems that can withstand severe overloads and environmental conditions, or for high-speed road use, which requires optimized passenger comfort options, safety features, and engine performance. The ability to meet regulatory standards for emissions control, fuel efficiency, and safety are important.
The development of the automobile revolutionized modern society and led to enormous changes in lifestyles, economies, and social structures. It has provided the freedom and flexibility of movement to individuals that was never before possible, and entire societies have been redesigned around the rapid, long-distance transportation that automobiles provide.
Since the 1920s, automobiles have been produced using mass production techniques that have allowed manufacturers to produce a number of similar models at lower costs per unit. This has resulted in a wide variety of styles, sizes, and price ranges available to consumers.