This paper describes the TestGen-IF tool, that allows the automatic generation of test cases based on model based active testing techniques. This paper describes the overall functionality and architecture of the tool, discusses its strengths and weaknesses, and reports our experience with using the tool on a case study, the Dynamic Route Planning (DRP) service of Vehicular Networks. This case study demonstrates how to use our testing tool to verify the system implementation against its security requirements. This paper also proposes improvements to this tool in the form of a GUI interface to facilitate its use and an approach which permits a gain in time and efficiency by generating test objectives