Automobiles have come a long way since the earliest steam-powered vehicles. In the late 1600s, Dutch scientist Christiaan Huygens developed a gasoline engine and later developed it into an internal combustion engine. The earliest gasoline-powered vehicles were crude versions of what we know today, and were driven solely by human effort. Nikolaus Otto created a motorcycle model in 1870 and it sold for about $400.

The definition of an automobile can be a complicated one. Many people believe that motorcycles can be considered automobiles, but these vehicles are often misunderstood. Although they are self-propelled, motorcycles do not transport many passengers and do not have sidecars. The National Highway Traffic Safety Administration recently received a letter from the Motorcycle Riders Foundation asking them to clarify the definition of an automobile and to include motorcycles as well as motor-driven cycles.

Motorcycles are more fuel-efficient than cars and often have better gas mileage. Some motorcycles can achieve more than 50 mpg, outpacing the best car models in the study. In 2006, Honda introduced an air-bag-equipped Gold Wing touring bike, while BMW made its debut with the K1600 flagship.

Henry Ford revolutionized the automobile industry by making them affordable for middle-class families. He implemented an assembly-line method of manufacturing at his factory and paid workers $5 a day. He hoped that this would increase productivity and allow workers to afford a new car. By the 1920s, the automobile industry was booming and the number of registered drivers tripled to 23 million.