Automobiles are wheeled vehicles that carry passengers, usually on seats mounted over four wheels. The term is most commonly applied to automobiles that are powered by an internal combustion engine using a volatile fuel, such as gasoline or diesel. Modern automobiles are complex technical systems with many different subsystems, and have evolved through a series of technological breakthroughs in high-strength steels and nonferrous alloys, electronic control units, computerised ignition and transmission, and safety features. The National Highway Traffic Safety Administration regulates the safety of motor vehicles in the United States.
The car is a symbol of freedom and independence, giving people the ability to travel wherever they want, whenever they want. It also allows people to have access to jobs and services that are not available in their home area, such as schools, shops, health facilities and leisure activities.
Cars can also be a major source of pride, especially for those who take the time to maintain and care for their cars. Modern car design has made significant advances, including improved aerodynamics, lightweight materials and more efficient engines. Other significant innovations include rear-view cameras, bluetooth connectivity, advanced sound systems and more.
A car is a convenient way to transport children, as it gives parents the freedom to choose where they go and when. It can also provide a sense of security and comfort that is not available with public transportation. Recent advancements in the field of car safety have significantly reduced deaths and injuries. These include the introduction of seat belts, airbags and child restraint systems. Other structural improvements include the use of stronger materials and more effective impact-absorbing structures.
With the growth of the middle class in America in the early 1900s, more and more people were able to afford automobiles. This led to a rise in leisure activities, such as shopping, vacations and sports. It also helped create new businesses, such as hotels, restaurants and gas stations. But cars brought their own problems, such as pollution and the need to build more roads.
Cars have also changed society in other ways. For example, they have allowed people to move from rural areas to urban areas for work and leisure. They have also contributed to the rise of fast food and convenience stores. But they have also had negative effects, such as increasing the risk of accidents and leading to the development of traffic laws and road rules.
The definition of what is an automobile varies according to the context in which it is used. However, most authorities agree that a car must have four wheels, be designed primarily for passenger transportation and be powered by an internal combustion engine. There are many types of automobiles, ranging from conventional sedans to hatchbacks and sport utilities. Some have a body that is integrated with the chassis, while others (like vans) have a separate superstructure. A few have an engine in the front, while most have it in the back.
