3: Aluminum

In the world of auto manufacturing, aluminum is kind of the new kid on the block. It's being used increasingly in the car world for its lightweight but tough nature. In 2009, aluminum components made up about 9 percent of the weight in most modern vehicles, compared with about 5 percent in 1990 and just 2 percent in 1970 [source: Aluminum Association].

Aluminum can be used in automotive manufacturing to create body panels for a lighter, more performance-oriented vehicle. Starting with the Acura NSX in the early 1990s, many supercars have been constructed out of aluminum, including the white-hot Audi R8. Wheels are also often made out of aluminum.

In addition, more automakers are switching from traditional iron blocks for engines to aluminum construction. It tends to be not quite as durable as iron, but its lighter weight means a big boost in performance.