Modern vehicles are highly complex systems consisting of many subsystems in various physical domains, e.g. electric, electronic, hydraulic and control systems that dynamically interact. For any subsystem, there are tailored simulation tools with specifically developed and adapted numerical solvers. In this context, co-simulation strategies are particularly attractive, where each submodel is solved with appropriate numerical methods. In industrial applications, one is hereby confronted with enormous numerical challenges with respect to efficiency, accuracy and numerical stability - especially in online applications. In this article, we present co-simulation strategies by means of selected application examples from the field of vehicle engineering.