@AnnaFless, thanks! Resolution of the STL file was too high and I could not open it as a solid in SolidWorks. So, in order to make two drafting cars, I had to use the software MeshLab which produced the both cars as a single surface. On the other hand, I could not extract the surfaces in Simscale using the feature angle criterion. I guess that was again a result of the high resolution. So for this case, I was only able to get the flow field and calculating the forces for each of the cars was not possible. But I did also analyses on a single car, two cars driving side by side and a single car in a yaw angle.