Impulse partner S.E.A. is helping to integrate the specific requirements and characteristics of V2X test systems into SINUS. In addition, S.E.A. is defining the requirements for testing V2X-based driver assistance systems. To increase the reliability of these V2X-based cooperative driving applications, a novel software and hardware-in-the-loop simulation tool for V2X testing is being developed in SINUS. This V2X test tool provides a simulation environment that enables the implementation, testing and evaluation of complex cooperative driving use cases. Such a simulation environment also allows the testing of potential special cases, so-called corner cases, for advanced V2X applications that are difficult to test in real life. Thus, SINUS will provide a test environment for devices implementing innovative V2X-based applications, so-called Day3+ applications, such as cooperative driving applications. Such a test environment offers the possibility to test these systems thoroughly and reproducibly before expensive and, due to their complexity, hardly realizable field tests must be performed for such applications.