In this chapter the creation of "virtual prototypes" of complex micro-electro-mechanical transducers is presented. Creating these behavioural models can be partially automatised using a reduced-order modelling (ROM) method. It uses modal decomposition to represent the movement of flexible structures. Shape functions model the energy conservation and full coupling between the different physical domains. Both modal shapes and shape functions for strain energy and lumped capacitances of the structure can be derived in a highly automated way from a detailed 3D finite elements (FE) model available from earlier design stages. Separating the generation of the reduced-order models (ROM) from the same FE model but for different operation directions circumvents current limitations of the used ROM method. These sub~models are integrated into a full model of the transducer. VHDL-AMS is used to describe additional strong coupling effects between the different operation directions, which are not considered by the used ROM method itself. The application of this methodology on a commercially-available yaw rate sensor as an example for a complex transducer demonstrates the practical suitability of this approach.