This study analyzes the power consumption of a specific Planetary Exploration Vehicle (PEV) subsystem known as Flexible-Wheel (FW) suspension, more specifically the interaction between a FW and the deformable terrain upon which it traverses. To achieve this a systematic and analytical calculation procedure has been developed, which culminates in the definition of three dimensionless properties to capture the FW-soil interaction. Aimed towards the design engineer participating in concept evaluation, and the control engineer conducting initial analyses, this study has found that the resistance coefficient for the interaction between a FW and the deformable terrain can, in general, be several orders of magnitude higher than the rolling resistance of a pneumatic tire operating upon rigid terrain. The sensitivity analyses also unveiled certain design parameters which have much more effect on the resistance coefficient than others, enabling the engineer to concentrate their efforts more effectively to achieve greater design optimization.