Automobiles are self-propelled wheeled vehicles, usually with four wheels, and are powered by an internal combustion engine or electric motor. Automobiles are one of the most ubiquitous modern technologies, and they are the basis of many industries. These vehicles are used for transportation of goods and people throughout the world.
Automobiles come in a variety of different styles and fuel efficiency ratings, including gasoline and electric. Motorcycles, for example, can achieve up to 52 mpg. They can also tow a trailer. Motorcycles use four to six-speed transmissions, whereas small bikes use two-speed gearboxes. Motorbikes also feature hand controls for the throttle and clutch, and a foot pedal for rear-wheel braking. Some motorcycles are kick-started, but modern models are equipped with electric push-button starters.
Development of automotive technology was rapid, with hundreds of small manufacturers vying for the attention of the world. Charles Kettering, for example, designed the first electric self-starter and independent suspension for Cadillac. Alfred P. Sloan, meanwhile, established the first four-wheel brakes and the Companion Make Program.
Automobiles also provide millions of jobs worldwide. Among them are millions of people who work in automobile factories and gas stations. They are also important sources of commerce, but they also pose problems of their own. Every year, millions of people die in car accidents. Cars also pollute the air and make parking space very scarce in cities.