As you might expect, the 4C is held together by gratuitous use of carbon fiber, aluminum, and serious technical know-how. The car is constructed around a carbon fiber monocoque, which gives the car tremendous strength and rigidity while also keeping it lightweight. In fact, that carbon fiber monocoque weighs just 143 pounds.
Other areas of the car are built using aluminum which is also lightweight and strong. The roof and front and rear crash sections have been reinforced with the metal so that they remain appropriately weighted and rigid without sacrificing any levels of performance.
It can't be nothing but carbon and aluminum, however, and Alfa Romeo turned to other high-quality metals and compounds to finish the job. The body is constructed of a material called Sheet Molding Compound, which gives the builders a 20 percent reduction in weight compared to sheet metal. Injected polyurethane was utilized for the bumpers and fenders.
Even the windows were given serious attention and forced to hit the scales. The glass on the 4C is 15 percent thinner than that of the standard automobile, which helps give Alfa Romeo more weight reduction.