The family of Epi.q mobile robots is based on a three-wheeled locomotion unit which is capable of switching between wheeled locomotion and legged locomotion depending on the dynamic conditions, without control intervention. This feature allows to conjugate the benefits of both the locomotion modes: high speed and energetic efficiency on even terrains with the wheeled locomotion, and mobility performance on uneven terrains and in presence of obstacles with the legged locomotion. Two prototypes of the Epi.q family have been already realized and tested, with positive results; a further evolution with four actuated locomotion units (instead of two active and two idle units) is currently under construction. The present paper outlines the evolution of the family of Epi.q mobile robots and proposes several possible architectural evolutions exploiting a modular approach; this approach could be used also to simplify the design phase, obtaining different mobile robots from a limited set of base modules.