The development of vehicle control systems has evolved to become an exercise in the design and integration of complex, distributed hardware and software components. The various components are typically developed by geographically dispersed, multicultural teams from both OEMs and suppliers. This paper gives a brief overview of using the Unified Modelling Language (UML) as a means of capturing the requirements of real-time distributed systems in a graphical notation shared by all team members. UML is commonly used to model system concepts, albeit typically as system "sketches" without any formal definition of the model's semantics. This paper specifically addresses the additions to the latest version of UML that supports higher levels of abstraction, model-based development, executable models and the specification of non-functional requirements. These improvements to UML make it more semantically complete, which means that a UML model can unambiguously describe a system, resulting in simpler automatic model verification and automatic code generation. The modelling of automotive network management requirements in a typical vehicle application is used to illustrate the benefits of the UML model development approach.