Automobiles are a key technology of modern times. They affect every aspect of human life, from city planning and the design of towns to police, fire, and utility services to personal use such as vacation travel or shopping. They make possible a flexible distribution of goods, and they help to restructure industries. They can give freedom of movement to their owners, but they also promote sprawl (a pattern of low-density development that degrades landscapes). And, if too many automobiles are used in a small area, traffic congestion can slow them all down and cause air pollution, which contributes to climate change.
Most automobiles burn a fuel to produce energy that turns the wheels, and they transfer this energy using a transmission system. The speed at which this happens, and how much power is produced from the engine, is measured in kilowatts or horsepower. The body of an automobile, which is analogous to the skeleton of a human being, supports these systems and components, offers storage space, and provides safety and comfort for passengers. It is designed to withstand the force of a crash by using crumple zones and a firewall between the engine and passenger compartment.
Karl Benz is generally credited with inventing the modern automobile, but it was Henry Ford who made them affordable for most people by using mass production techniques. Other inventors and engineers have worked to improve the design, performance, and appearance of the vehicle.