The design and verification of critical cyber-physical systems is based on a number of models (and corresponding analysis techniques and tools) representing different viewpoints such as function, timing, security and many more. Overall correctness is guaranteed by mostly informal, and therefore basic, arguments about the relationship between these viewpoint-specific models. We believe that a more flexible contract-based approach could lead to easier integration, to relaxed assumptions, and consequently to more cost efficient systems while preserving the current modelling approach and its tools.