The reflections are already working, so it's not a material problem (else even the static ones wouldn't show up). What's your Graphic Card? Does it fully support DirectX11 or just DirectX10?
No it's probably not his graphics, it may be the way his textures/materials are set up. Unless he has issues with the dev cars not handling dynamic reflections, it's the materials.cs file. I think it's the line specific to Dynamic Reflections that is missing. @Dean Wang , re-read this post, it may be helpful; Use the code quoted from a previous post for your body material. You should look at another official vehicle to see how each layer is set up, and then replicate that here. I hope this helped