Today, control algorithms of electronic in-vehicle functions are implemented on various networked control units with different software architectures and designs. Special effort is needed when integrating those artifacts and software components from different sources to overcome the limits of efficient integration of model-based design into the embedded development. This paper focuses on the advantages of model-based development by mixing object-oriented and signal-oriented modeling concepts together and referencing (generated) legacy software components to get an overall software design. Therefore, we present an integration methodology of UML and Simulink modeling concepts to a traditional automotive software engineering process. Furthermore we describe the model-based engineering of a car-door control system as an example.