F.1.3 Monocoque

Explanation

Monocoque: "a vehicle structure in which the chassis is integral with the frame". Instead of a tube chassis with body panels mounted on the outside of the tubes, the chassis will be made of continuous sheets of material, that are also structural so less or no tubes are required. 

Monocoques are more complicated to design and fabricate, than traditional space frames. There are a lot of reasons for this, but one of the notable ones is the amount of additional material testing required to prove that a specific monocoque is safe.