BMW's design folks use terms like "subtractive modeling" that make the car seem like a derivative of subatomic theories, and in a sense, it sort of is. The core of the car is layers of carbon fiber, used for its combination of super lightness and super strength. They then add a layer of "user interface components," i.e. your gauges, lights, and control panels. Only after all that's settled do they add in structurally-sound aluminum structures to ensure it's actually safe.