A vehicle self-supporting monocoque body assembly comprising a base frame structure is provided. The body assembly also comprises a pair of wheel axles interfaces located at generally front and rear locations of the base frame structure for receiving a pair of wheel axles. The body assembly also has an energy storage element compartment positioned between front and rear wheel axles interfaces. The body assembly also includes an engine compartment for completely housing an engine system. The body assembly also comprises a vehicle outer frame interface. The body assembly also includes front and rear suspension arm interfaces for interfacing with two pairs of front and rear symmetrical suspension arms extending along a length of the base frame structure. The bottom surface of the base frame structure is positioned at or below a horizontal plane between the wheel axles. Preferably, the vehicle outer frame interface is shaped to receive a cabin frame structure.