Simulations are essential for understanding complex systems such as Cyber Physical Systems. The creation of reliable multidisciplinary simulation tools that can be used to support the entire development process has been identified as a major scientific goal in several research roadmaps and agendas for the coming 15 years. This chapter presents two showcases, which highlight the necessity of trustworthy simulation tools, especially in the case of ma- chine-to-machine communications. First the performance of UWB radio technology in context of vehicle automation is evaluated. Second the experiences from performing the entire cycle of protocol development for machine-to-machine communications are presented. The two presented showcases support a conclusion that a successful simulation platform should have a us- er-friendly simulation framework and models that support virtualization. This will enable the incorporation of simulations into day-to-day engineering prac- tice and thereby shrink the gap between the real and the virtual developing environments.