Fuel tank

Crushable, yet bullet-proof structure, housed inside the chassis and made of Kevlar to prevent it being punctured in an accident. Fire is the biggest fear of everyone in F1.

Its size is not stipulated by the rules, and designers face a complex trade-off. Make it smaller, and the car's performance will usually be improved. But a larger tank gives increased flexibility on pit-stop strategy, which is all-important in the modern age of F1.