Automobiles play a major role in modern life. They provide the convenience of rapid, long-distance movement that has fundamentally changed many societies and transformed many industries. They have restructured urban and rural areas, allowing for a more flexible distribution of goods and services. And they have revolutionized personal transportation, facilitating freedom of movement that was never before possible.
There are an estimated 1.4 billion passenger automobiles in operation worldwide. This number is expected to grow to 1.7 billion in the near future. In addition to passenger cars, there are an increasing number of commercial vehicles, such as delivery trucks and taxis. The field of study that deals with the manufacture and technology of these vehicles is called automobile engineering.
The modern automobile was first introduced in the late 1800s and consists of four to eight wheels with a motor and an enclosed body. It is powered by an internal combustion engine and can be fueled with gasoline, propane, liquefied petroleum gas (LPG), or battery-powered electric motors.
A car’s design depends on its intended use and the conditions under which it will be driven. For example, automobiles designed for off-road driving must be equipped with durable systems that are resistant to severe overloads and extreme operating conditions. In contrast, vehicles that will be driven on highways need to offer increased passenger comfort and optimized high-speed handling and stability.
An automobile’s complexity is the result of thousands of individual parts arranged into several semi-independent systems that work together. These include a circulatory system for coolant, lubricating oil, and fuel; a transmission system to convert the engine’s power into the torque needed to propel the vehicle; and a chassis that is capable of supporting the weight of the vehicle and responding to the conditions of the road surface.
Hundreds of automobile companies have sprung up throughout the world. The most successful have been those that were able to produce and sell their products at affordable prices. These manufacturers have benefited from the invention of large-scale, assembly line manufacturing. This concept was pioneered by Ransom Olds in 1902 and greatly expanded by Henry Ford in the 1910s. New technical developments also have helped keep pace with consumer demands. Examples include electric ignition and the electric self-starter (developed by Charles Kettering for the Cadillac Company in 1910-1911), independent suspension, and four-wheel brakes. The pistonless rotary engine developed by Mazda in the 1930s has not found a large market, but it may eventually prove to be an important innovation.
The safety of passengers depends on the ability of the driver to control the vehicle and react quickly when necessary. Among the many factors that influence a car’s ability to respond to sudden events are human drivers who sometimes make mistakes, wheels that lose traction with the road under heavy braking or turning forces, and a tendency of some vehicles to roll over when the speed at which they are driven exceeds safe limits. These and other problems have led to significant improvements in automotive design.