5: Steel

On modern cars, most of the weight comes from steel. In 2007, for example, the average car contained 2,400 pounds (1,090 kilograms) of steel, and the average pickup truck or SUV used nearly 3,000 pounds (1,360 kilograms) [source: Sherefkin]. Consider that most cars now weigh around 3,000 pounds, and most SUVs weigh around 4,000 pounds (1,810 kilograms) -- that's a lot of steel!

In cars, steel is used to create the underlying chassis or cage beneath the body that forms the skeleton of the vehicle and protects you in the event of a crash. Door beams, roofs and even body panels created during auto manufacturing are made of steel on most cars today. Steel is also used in a variety of areas throughout the body to accommodate the engine or other parts. Exhausts are often made from stainless steel, for example.

Steel manufacturing has evolved greatly, so carmakers these days can make different types of steel for different areas of the vehicle that are rigid or that can crumple to absorb different impacts. These innovations in automotive manufacturing help keep you safe on the road [source: Fountain].