An automobile, also known as a motor car or a car, is a wheeled passenger vehicle that is propelled by an internal-combustion engine using a volatile fuel. It has a seating capacity for one to seven people and is designed primarily for transportation of passengers. Modern cars are complex technical systems consisting of many subsystems with specific design functions. The choice, arrangement, and configuration of these components vary according to the intended use of the automobile. An automobile may be built to provide good fuel economy for local trips, or it can be designed for speed and handling, or it can be equipped with computer technology and advanced safety features.

Automobiles have a significant impact on the world’s economy, society, and the environment. A car can save a person considerable time and money over taking public transportation or riding a bicycle. It can also reduce stress in a person’s life by freeing up time for other activities. The ability to travel more quickly from place to place means that a person can get to work, go to school, and spend time with family members.

The automobile is the most important invention of recent times. New technical developments continue to have a major impact on the design of automobiles, including body, chassis, engine, drivetrain, control systems, and safety systems. These advances include electric ignition and self-starters (by Charles Kettering for the General Motors Company in 1910-1911), independent suspension, four-wheel brakes, and the Wankel rotary engine by Mazda (1989).

Modern automobiles are designed to meet numerous requirements for safety, performance, size and weight, comfort, and appearance. They are also designed to comply with environmental regulations concerning exhaust emissions and fuel efficiency. These factors often conflict with each other, and compromises are required to satisfy as many of the requirements as possible.

One of the most important parts of an automobile is its suspension system. The suspension system consists of springs and shock absorbers that help to reduce the vibration caused by the movement of the wheels over the road surface. These springs are mounted above each wheel and surrounded by tubes and chambers filled with hydraulic fluid. The shock absorbers dampen or quiet the vibrations of the springs, thereby reducing the ride comfort and noise level.

The number of cylinders in an automobile’s engine is another factor that influences its performance. A smaller automobile will usually have a four-cylinder engine, while mid-sized and larger cars will require the power of six or eight-cylinder engines. The transmission system in an automobile is a key part of the driving experience. It provides a way to direct the power of the engine to the wheels through a series of gears. Each gear is a combination of input and output ratios that allow for different levels of acceleration from a standstill. Most automobiles have three forward and one reverse gear, although some vehicles have more.