Automobiles are motor vehicles used for the transportation of passengers and goods. Automobiles are usually powered by internal combustion engines, though some are electric motor vehicles. They have four wheels and are fueled most often by gasoline (petrol in American English) but can also be powered by diesel fuel, natural gas, air or kerosene. Several hundred thousand different automobiles are produced each year worldwide. Automobiles can be built in a variety of shapes and sizes, including sedans, coupes, hatchbacks, station wagons, SUVs and vans.
Most modern automobiles have brakes that can stop the vehicle quickly in an emergency or to prevent it from rolling when parked. Some have regenerative brakes that convert some of the energy of motion into electricity to recharge the battery.
The automobile revolutionized American life in the 20th century and created many spin-off industries, including rubber production for tires and oil refining. Many cities and towns had to rebuild roads to accommodate the new vehicles, and new jobs were created in construction, manufacturing and other areas of the economy.
Having an automobile allows people to save time that they would otherwise spend traveling to work, shopping, running errands or visiting friends and family. This free time can allow people to spend more time doing the things they enjoy. For people who live in rural parts of the country where public transportation options are limited, it may be essential to have a car to get around.
While the science and technology that goes into an automobile dates back centuries, it wasn’t until Henry Ford’s assembly line approach to production that cars became affordable for most Americans. As a result, the automobile brought about a cultural change. Families could go on vacation together, urban dwellers were able to rediscover the countryside and its pristine landscapes, teenagers gained independence through driving freedom, and dating couples found a portable place to have intimate conversations.
The automobile has some drawbacks, however. The movement of so many vehicles creates traffic jams that delay people getting where they are going, and the pollution caused by automobiles can contribute to global climate change. Also, automobiles can be damaged or destroyed in accidents and theft.
Some countries have laws regulating the design, construction and use of automobiles, while other countries have national or state safety and environmental standards that must be met before an automobile can be sold. In the United States, all automobiles must be registered and insured. The American Society of Automotive Engineers (SAE) sets the most industry standards for testing and measuring automobiles and their components. The SAE also oversees the licensing of automotive-industry engineers and sets many of the technical specifications that must be met by manufacturers of automobiles. The SAE is not a membership organization, but most automobile-industry engineers belong to one of the many professional engineering societies that offer certification for those who work in the automotive industry. These societies can be found in most countries around the world.