The product development process at industrial companies has traditionally focused on hardware-oriented solutions. Business strategies strive towards more service-oriented solutions e.g., functional product business models. In this paper two case studies are developed and the objective is to highlight important challenges and opportunities by implementing a simulation-driven strategy in functional product development and operation. It can be concluded that challenges and opportunities within simulation-driven functional product development and operation are related to both quality and management of the simulations. With the proposed strategies for validation and coupling of the simulations, some of the challenges within functional product development can be overcome.