An automobile, formerly called a motorcar or a car, is a self-propelled passenger vehicle for travel on land. Automobiles have four wheels and an internal combustion engine fueled most often by gasoline, but can also use other fuels and are powered by electric motors. In the United States the automobile industry is one of the most important and productive industries, producing 73 million vehicles in 2009.

The automobile has had numerous social, economic, and political effects in American history. It has brought people closer to the natural world by allowing them to go to remote places that could not easily be reached before, and it has allowed urban dwellers to rediscover the beauty of pristine landscapes. It has facilitated shopping in towns and cities, as well as leisure travel and vacations. The automobile has made work possible for many families and lowered the cost of living. It has created new jobs in manufacturing and service, and has helped to establish a middle class in the United States.

It has also influenced the lifestyle of Americans and other people throughout the world. Driving a car allows people to move about independently, without having to wait for public transportation or worrying about the cleanliness of other passengers on crowded buses. This independence makes it easier for people to make appointments at their own convenience.

There are pros and cons to having an automobile, including the fact that it is a major source of greenhouse gases when burning gasoline. However, people can limit their consumption of gasoline and reduce greenhouse emissions by switching to a hybrid automobile that uses both an electric and gasoline engine.

Several different types of automobiles have been developed over the centuries. Early designs were powered by steam, electricity, or a combination of both. In the 19th century, the development of the assembly line in manufacturing allowed Henry Ford to bring the automobile within the reach of most middle-class Americans with his Model T.

The automobile is an extremely versatile vehicle that can be configured in a wide range of sizes and styles. In addition to the main body of the vehicle, there are a number of other essential parts, including the chassis, transmission, electrical system, and engine. The design of an automobile depends largely on its intended use. Off-road automobiles must be rugged and simple, while those designed for high-speed road use must have optimized high-speed handling and stability.

There are also special automobiles that are used for specific purposes, such as a crane vehicle at a construction site or a fork-lift in a warehouse. These automobiles require a more specialized engineering and maintenance than standard cars. Specialty cars also include ambulances, fire engines, and patrol cars that are called upon to rescue people from traffic accidents and other emergencies.