Automobiles are land vehicles designed to carry people that are propelled by an internal combustion engine using a volatile fuel. Modern automobiles are complex technical systems, with subsystems that have specific design functions. These include the body, chassis, engine, drivetrain, and control systems. New developments in technology have enabled automobile manufacturers to make their cars more efficient, safer, and more comfortable. These technological advances have come about from breakthroughs in electronic computers, high-strength plastics, and advanced alloys of steel and nonferrous metals. In addition, automotive production techniques have been adapted to mass-producing automobiles that can be produced inexpensively and reliably.

The most common type of automobile is the passenger car, which is usually powered by an internal combustion engine that uses gasoline, diesel, or other fuel to move the wheels. Automobiles are available in a variety of sizes to fit different needs. There are also specialty automobiles, such as convertibles and sports cars, which offer more freedom of movement than standard cars. Some automobiles, such as pickup trucks and station wagons, have rear cargo space for hauling large items.

Many families own multiple automobiles for their convenience and flexibility of use. The ability to go places that aren’t accessible to public transportation expands the life radius for a family and makes work and leisure activities possible, without having to depend on expensive taxis or buses.

Most cars are equipped with front-wheel or all-wheel drive and have independent suspension to cushion the ride and improve handling. The engines of automobiles burn gasoline, diesel, or kerosene. An electric starter motor supplies the force needed to start an engine, and a battery or alternator provides energy for the engine to turn the wheels. Computers are used to control the operation of many automobiles, and they require electrical power as well.

The cost of a car can be prohibitive for many buyers, and some manufacturers offer models with few frills to cut costs. Smaller automobiles tend to have four-cylinder engines, while larger cars need six or more cylinders to work efficiently. The number of cylinders and the type of engine determine how quickly the automobile can accelerate, how smoothly it runs, and how much gas it consumes. Air pollution can be a problem, and many cities are attempting to reduce the number of automobiles by encouraging low-density urban development that does not require automobile use. Public transportation, such as buses and trains, can get you from point to point faster than automobiles when traffic congestion is a problem. Some countries have trams and subways that run on electric or rail power and can move more people than an automobile in a given time. They can also provide transport when the weather is bad or when a city’s streets are damaged. These transportation methods are often cheaper and more environmentally friendly than an automobile. They can also help avoid the congestion caused by too many automobiles on a limited road area.