There is a barely audible driving noise, when you driving the BR 422 on HRR. In contrast to the RRO route, where the driving noises can be clearly heard. If you switch to the exterior camera the sound works fine, but from the driver's cab and the view outside the window, you only can hear the closing and opening doors and some switches...
...not really because you can hear the sound on the RRO DLC, where it functions correctly. Groeten aan Holland!