Automobiles are four-wheeled motor vehicles that use an internal combustion engine to convert fuel (gasoline, diesel, kerosene or any other fuel) into motion and power. The engines generate torque through the transmission, which transfers it to the driving wheels of the vehicle. Automobiles also have control systems, electrical equipment and service devices. They are the most commonly used vehicles on the planet with an estimated 1.4 billion cars in operation globally each year.

The modern automobile is an indispensable part of the modern world and has transformed how we live, work and play. The car allows us to travel far and wide, connecting us with friends, family and the wider community. It provides a safe, convenient and comfortable mode of transport over short distances. It has become the primary means of transportation for many families, with an average of three trillion miles (5 trillion kilometres) driven each year in the United States alone.

Cars have become a symbol of the American Dream, a potent symbol of prosperity and freedom. No other invention has altered daily life in America more than the motor vehicle. But it hasn’t been without its drawbacks. Traffic jams, road rage and accidents have produced political unrest and led to calls for licencing and safety regulation. Air pollution and a drain on dwindling world oil reserves have also been issues.

In the late 19th and early 20th centuries, the automobile was mostly a luxury item used for racing and amusement. The first cars were referred to as horseless carriages or simply autos, and they were expensive, heavy and unreliable. Ransom Olds developed the concept of interchangeable components, allowing his company to make the one-cylinder, three-horsepower 1901-1906 Oldsmobile into a mass-produced automobile at a moderate price and within reach of middle-class consumers.

Henry Ford streamlined the production of automobiles by introducing the assembly line in Detroit in 1913. His system allowed workers to stay in place and focus on a single task while parts were passed by on a conveyor belt. He could produce many cars quickly and cheaply, and his Model T was a tremendous success.

The heyday of the automobile in the United States ended with the end of World War II, as manufacturers funneled most of their resources into the war effort. In the postwar era, engineering was often subordinated to questionable aesthetics and nonfunctional styling at the expense of economy and safety, and quality began to deteriorate. By the mid-1960s, Americans were consuming a record number of defective cars with a high incidence of safety-related problems.