Automobiles, also called motor cars or automobiles, are four-wheeled vehicles designed for passenger transportation and powered by an internal combustion engine fueled by gasoline (petrol). Most of these engines use a carburetor with a spark plug to ignite the fuel-air mixture. The resulting explosion propels the car forward and is transferred to the wheels by a transmission system. The modern automobile has a number of safety and performance features including a padded dashboard, airbags, seatbelts, and antilock brakes.

The invention of the automobile was one of the most significant changes in American life in the 20th century. The automobile allowed people to move freely and independently, to shop in towns and cities and to work and play at a greater distance from home than ever before. It also encouraged the development of a range of industries and services that provided parts, materials, and fuel for the automobiles.

Karl Benz is often credited with inventing the automobile, but it was Henry Ford who popularized its mass production on an assembly line and made cars affordable to the middle classes. This revolutionized the world and gave many people freedom of movement and access to jobs and goods previously available only to the wealthy.

The modern automobile is a complex technical system with several subsystems, each with a specific design function. These include a powertrain that consists of the engine and transmission, chassis, and axles; bodywork and interiors; controls and services; and electrical equipment. Modern cars have sophisticated control systems that utilize electronic computers and advanced materials such as high-strength plastics and alloys of steel and nonferrous metals.

In the past, cars were often regarded as status symbols, but the economic stagnation that followed World War II and questions about the pollution and draining of global oil supplies brought the automobile into more mainstream view. Today, there are an estimated 1.4 billion automobiles worldwide.

When choosing a car, buyers typically base their decisions on safety, price, and performance. The most important factor is reliability, which can be determined by a vehicle’s track record over time, as well as by reviews and tests conducted by independent sources. Other key considerations are handling, ride comfort, and gas mileage.