Automobiles, or motorcars, are self-propelled vehicles for passenger transportation on land. Most automobiles have four wheels and an internal combustion engine powered by gasoline, a liquid petroleum product. Modern automobiles are highly complex technical systems and a major industry with worldwide production exceeding 73 million units in 2007. Research and development engineers continuously work to improve the body, chassis, engines, drivetrains, electrical systems and safety features of cars.

The automobile has influenced every aspect of life in the United States. It brought industry, technology and everyday jobs to rural America, as well as urban amenities like schools, shopping, medical care and public services. The automobile boosted agricultural productivity by enabling farmers to transport their crops to market more quickly. It also stimulated family vacations to formerly remote destinations. The automobile ended rural isolation and allowed people to escape the confines of home. It also created new industries like gas stations, convenience stores and road construction.

The automobile is the primary mode of transportation for most Americans. The majority of cars in use are passenger automobiles, but there are also commercial automobiles such as trucks and buses. There are also special automobiles such as police cars, fire engines and ambulances. The majority of automobiles are powered by gasoline, but some have electric and diesel engines. The latter use a heavier petroleum fuel and create less pollution.

A car is a necessary tool for many families, as it allows them to get to work and run errands more quickly than if they had to rely on public transportation or friends for rides. It is also a great way to spend time with the kids. However, having a car comes with some drawbacks such as maintaining the vehicle and deciding where to park it.

While the automobile has had a significant impact on society, it has not been without its problems. In the 1920s, it ranked as one of the top three value-producing industries in America and provided one out of six jobs. It was the main driver of economic growth and development, transforming America into a consumer goods-oriented nation. It became the lifeblood of a number of other industries such as petroleum and steel, and it created numerous ancillary businesses including gas stations, service stations and motels.

The automobile has led to increased competition among manufacturers and the development of new technological advances. In recent years, the automotive industry has made significant advancements in computer technology and high-strength plastics. It has also been important in the development of improved safety and environmental control systems. In addition, new technological developments have allowed for hybrid automobiles which combine the benefits of gasoline and electricity. This type of automobile will not be a replacement for traditional passenger automobiles, but it will serve as a complementary alternative that can help reduce harmful emissions and conserve energy. As the economy continues to rebound, automobile sales are expected to improve. This will be good news for the automotive industry and consumers.