Automobiles are four-wheeled vehicles designed mainly for passenger transportation and powered by an internal combustion engine using a volatile fuel. The modern automobile is a complex technical system that requires thousands of components to work properly. Some of the most important are the engine, the transmission and the steering system. All of these must be working in perfect harmony to make a car run smoothly, safely and economically.

The automobile revolutionized twentieth-century life. The automobile became the backbone of a new consumer goods-oriented society and it helped to create many new industries. It also provides jobs for millions of people who manufacture, service and repair cars. Millions more work at gas stations and at restaurants and motels where travelers stop. However, the automobile also has some disadvantages. Millions of people die in car accidents every year and parking space is scarce in city centers.

Although Benz and Duryea invented the first modern automobile, Henry Ford popularized this mode of transportation by lowering its cost. He used mass production methods that allowed him to build automobiles at a lower price than European manufacturers. This enabled him to sell the automobile to more middle-class Americans and to open up the market to people who could not afford a traditional luxury model.

Since the 1920s automobile manufacturing has become an enormous industry in the United States, providing jobs for more than a fifth of the nation’s workforce. It has also helped to revitalize many cities, allowing them to grow beyond their limited industrial base. Automobiles have also contributed to economic progress in other countries.

Modern automobiles are sophisticated machines with many safety features to prevent injuries and deaths to passengers. Most of these systems are computerized and someday cars may even drive themselves.

Automobiles are made from a variety of materials, but steel is the most common. Many manufacturers now use high-strength plastics or fiberglass as well. Some have switched to hybrid engines that combine gasoline with electricity, reducing emissions and improving mileage.

The body of the automobile is a framework of steel and other metals that covers the mechanical parts. The body also includes the passenger compartment, trunk and fenders that cover the wheels. The body must be strong enough to protect the passengers from accidental collisions with other vehicles or stationary objects, and it must be visually appealing. It must also allow for clear visibility.

New technological developments in automobiles are constantly being introduced. Various research and development engineers work on the body, chassis, engines and other components of the car to improve its performance. The resulting improvements are usually offered as optional upgrades by the manufacturer. In addition, consumers can choose from different vehicle models to suit their preferences and needs. These include sedans, coupes, minivans and station wagons. SUVs, which combine the towing capacity of a pickup truck with the passenger and cargo space of a van or a large sedan, are increasingly popular.