An automobile (also called a motorcar or car) is a wheeled vehicle designed for passenger transportation. It is usually propelled by an internal combustion engine fueled most often by gasoline, a liquid petroleum fuel. Modern automobiles are complex technical systems with many subsystems that have specific design functions. For example, safety systems such as airbags and crumple zones are important to ensure that occupants will be protected in the event of an accident. The design of an automobile is determined by its intended use, as well as environmental and legal considerations.
Automobiles can transport people more quickly and conveniently than walking or riding a bicycle, and they can carry more luggage. They can also go places that are inaccessible to other wheeled vehicles, such as off-road environments or underground tunnels. However, automobiles can create pollution if too many are used in a small area, and they can cause traffic congestion if too many try to travel at the same time.
The first automobiles were powered by steam, electric power or a chemical energy from oil or natural gas. In the 1860s Siegfried Marcus of Austria invented the first two-stroke engine for a gasoline-fueled automobile, but the crude vehicle had no seats, steering or brakes. Karl Benz of Germany improved upon Marcus’s invention, and he built and patented the first four-stroke gasoline-fueled automobile in 1885, called the Benz Patent-Motorwagen.
Until mass production came along, cars were built by hand and often customized for their owners. Then Henry Ford revolutionized the auto industry by introducing the assembly line, which made it cheaper and faster to produce the same model of automobile over and over again. This enabled more people to afford them. Over the years, manufacturers added features like turn signals, rearview mirrors and windshields, air conditioning, heated seats, and cruise control to automobiles.