Evolution In the Designs

A car (or automobile) is a wheeled motor vehicle used for transportation. Most definitions of car say they run primarily on roads, seat one to eight people, have four tires, and mainly transport people rather than goods. 
Changes in raw materials used to make car bodies:
Iron-Steel-Aluminium-Carbon fiber

Iron- Is heavy, more fuel consumption, rust easily
Carbon fiber- Very light so better fuel use, Cheap, improves aerodynamics, Shiny finish