In this master’s thesis, a validation method for engine models in a HIL simulator is developed. To make the validation automatic, a script has been written in the programming language Python that executes the engine model in the same way as the real engine in a test cell at Scania CV. Variables in the model are recorded in real-time and compared to recordings from the engine test cell. The validation method handles static as well as dynamic engine model validation. The submodels in the current engine model that causes the most deviation from engine test cell data are identified. One of them, i.e. the turbine model, is improved by creating a semi-physical model of a Variable Geometry Turbine (VGT). Furthermore, future improvements have been suggested.