Automobiles, by definition, are four-wheeled motor vehicles designed primarily for passenger transportation and powered by internal combustion engines fueled most commonly by gasoline (a liquid petroleum product). A vastly superior technology to the horse-drawn carriages of earlier days, automobiles have revolutionized society by making it possible for people to live in distant cities or villages. They allow people to travel more quickly than by train or bus, giving them greater freedom of movement in their personal lives and enabling them to work from home, to shop for more products, and to travel for leisure activities such as recreation, vacations, and dining. The automobile has also created new industries for manufacturing and selling parts, services, and fuel. It has given many people a sense of independence and the freedom to be spontaneous in their daily activities, and it has enabled families to spend time together.

Automobile technology was first developed in Germany and France toward the end of the nineteenth century by such men as Gottlieb Wilhelm Daimler, Karl Benz, Emile Levassor, and Nicolaus Otto. It was Henry Ford who brought the automobile to mass personal “automobility” in the United States. He was the first to employ moving assembly lines to speed production of his Model T runabout, and he priced it so low that most middle-class Americans could afford to buy one. In doing so, he introduced modern industrial methods that have been applied to almost every industry.

In America in the 1910s and 1920s, the automobile triggered an economic revolution that created dozens of spin-off industries. For example, the demand for vulcanized rubber soared and roads became important business for construction firms. In addition, women who drove cars could get to work in factories and on the streets, a great change from their previous limited roles. Women also began to use cars to promote women’s rights, driving around with banners that read “Votes for Women” or giving speeches on the radio about their rights.

The modern automobile is a complex technical system consisting of subsystems with specific design functions. The engine-the automobile’s heart-comprises an analogous circulatory system for coolant fluid, lubricating oil, and fuel. A skeletal structure called the chassis, similar to the human body’s skeleton, supports the various systems and provides safety and comfort for passengers.

The automobile has some disadvantages, however. Its use of fossil fuels causes air pollution and releases carbon dioxide, a greenhouse gas, into the atmosphere. It also requires maintenance and can be expensive. But most people who own cars would say that their lives are much easier than those without them, and that they are a worthwhile investment. The fact that there are so many different kinds of automobiles today is a testament to the wide range of factors that go into their design. Some of these include standards of safety, size and weight, power to performance, efficiency, aerodynamics, or ways to reduce friction from airflow, and appearance. Each of these features has to be balanced with the needs and tastes of potential buyers.