Typically, automobiles are four-wheeled vehicles that are used for passenger transportation, commerce and pleasure. They have a variety of components including a chassis, engine, wheels, tires, brakes, steering, and emission-control systems. The vehicle’s stability and performance depend on a number of factors, including its size, weight distribution, location, and intended use. Modern automobiles are highly technical systems with thousands of component parts.

In the twentieth century, automobile manufacturers were required to comply with stricter safety standards. These safety standards regulated the windshield, lighting, door strength, brakes, and head restraints. The automakers also improved their engine and control systems. These innovations made the automobile a popular mode of transport.

Automobiles are also considered the largest cause of air pollution. They account for a large portion of carbon dioxide emissions. The United States Environmental Protection Agency began regulating hydrocarbon emissions in 1980. The agency has mandated that new motorcycles emit less than 5.0 grams of hydrocarbons per kilometer. In 2010, new motorcycles were limited to 0.8 grams of hydrocarbons and nitric oxides per kilometer.

Although the definition of an automobile is somewhat loose, most people generally use the term to refer to a four-wheeled vehicle that is designed to carry passengers and property. The automobile can be built with several different types of engines, but it is usually a gasoline-powered machine.

Throughout the twentieth century, the automobile industry grew rapidly. The United States became the world’s leading manufacturer of automobiles. In 1903, Henry Ford founded the Ford Motor Company. In 1908, Ford introduced the Model T, which was manufactured using assembly line techniques. This was the first mass-produced car and helped increase the American automobile industry’s prominence. By 1940, the Big Three automakers had 90 percent of the U.S. market. However, by the late 1970s, Japanese auto companies had surpassed the U.S. automakers in both production and sales. Increasing oil shortages and embargoes in the 1970s increased the price of gasoline.

In the early 1980s, the auto industry suffered greatly. In response, the National Highway Traffic Safety Administration was created. This agency was given the authority to enforce safety standards and to recall defective vehicles. The NHTSA has become the largest consumer safety organization in the U.S. Since its creation, the government has imposed more than 50 safety standards on auto manufacturers.

The automobile is a favorite target for thieves. They are expensive to buy and to maintain. They are taxed heavily. They are also susceptible to fires. In the 1970s, gasoline prices increased for smaller autos. Consequently, citizens turned to imported autos more often.

In the 1960s, consumer safety advocates began pressuring the government to impose federal safety standards. This led to the National Traffic and Motor Vehicle Act, which created the National Highway Traffic Safety Administration (NHTSA). The National Highway Traffic Safety Administration was given the authority to coordinate state programs to reduce driver behavior and improve the safety of automobiles.

The 1990s brought a revival in the U.S. automotive industry. As the country became more economically developed, more and more people purchased automobiles. The United States lost ground to Japanese and European automakers in the mid-1990s, but these automakers have regained their footing. Today, Americans travel three trillion miles every year. A third of these miles are devoted to motoring. In fact, the automobile is the most common form of transportation in the United States.