Automobiles are self-propelled vehicles for passenger transportation that usually have four to eight tires and an internal combustion engine or motor. The field of engineering that deals with the design, manufacture and maintenance of automobiles is called Automotive Engineering.
The earliest modern automobiles were perfected in Germany and France toward the end of the nineteenth century by engineers such as Gottlieb Daimler, Karl Benz, and Nicolaus Otto. Their design included a water-cooled internal combustion engine mounted on the front of the car that drove one or more shafts. The power generated by the engine was transmitted to the wheels by the means of a gear system, which is used to adjust the ratio of wheel speed to drive shaft speed.
In the United States, Henry Ford revolutionized automobile production by developing the assembly line. His Model T runabout, which cost about $575 in 1912—less than the average annual wage at that time—made automobiles affordable for middle class families. This change had a profound effect on American life. It gave people more personal freedom and access to jobs and services. It also led to new industries for supplying materials like petroleum and gasoline, and services such as highways, auto repair shops, motels, restaurants, and fast food joints.
Pros: Cars give you the independence to travel wherever and whenever you want, without having to rely on others. You can also avoid being in crowded buses, which can be uncomfortable. Cons: Most automobiles run on gasoline, which releases carbon dioxide, a greenhouse gas, into the atmosphere. Buying a more fuel efficient car and driving less can help limit this problem.