Automobiles are one of the most ubiquitous and universal of modern technologies. Also known as cars, they are self-propelled vehicles used for passenger transportation on land and powered by an internal combustion engine fueled most often by gasoline. The invention of the automobile unleashed a host of related industries and changed the lives of many families. Some of these changes were positive, but others harmed people and the environment.

Invented in the late 1800s, automobiles revolutionized modern life. They enabled people to travel quickly and easily across large distances, and they fueled a predilection in the United States toward individual freedom of movement, action, and living. Without clear guidelines about the responsibilities necessarily attached to such freedom or any higher governing principle of how to live together as a society, Americans got into their cars and drove away, creating huge suburban areas where each family could enjoy its own little territory of a house surrounded by green grass.

After Karl Benz, a German engineer, invented the automobile in 1885, other inventors and engineers developed their own designs. Then a businessman and engineer named Henry Ford invented the moving assembly line, which allowed car makers to produce many cars more rapidly at lower cost. As a result, the price of automobiles dropped dramatically, and more and more middle-class families began to be able to afford them.

The automobile made work possible for many more people than had previously been able to find jobs. It allowed them to move to jobs and communities farther from their homes, and it helped them achieve better lifestyles by giving them access to leisure activities such as travel, entertainment, shopping, restaurants, and recreation. It also contributed to the development of new industries such as road construction, hotels, and motels. In addition, it brought harm to the environment through exhaust emissions, pollution, and the destruction of undeveloped lands for highways.

In the 20th century, automobile production soared around the world as manufacturers funneled their resources to meet demand for military and civilian vehicles. In the United States, a few large companies controlled the market. Engineering in the postwar era was subordinated to questionable aesthetics of nonfunctional styling, and quality suffered. In contrast, the Japanese automakers produced vehicles that were efficient and well-engineered. As a result, their cars out-sold American models. In 1999, the first hybrid automobiles appeared on the consumer market; they combine an internal combustion engine and an electric motor. The engine takes over while cruising, and the electric motor is charged by regenerative braking. In addition, some hybrids can operate in electric-only mode. They also run on diesel, a less-efficient but more environmentally friendly fuel. They are also used in some commercial trucks and buses. In the future, these automobiles may be the standard. They will have to be, if the world is to use its dwindling supplies of fossil fuels wisely. In the meantime, other technologies such as solar panels, wind turbines, and battery-powered systems will likely help reduce carbon dioxide emissions and make automobiles more efficient.