Can anyone relate to the slight whine from the gear box area when doing about 70/80 mph. I am fammiliar with the vanos rumble at idle and that it is common on the e39 m5. not sure if i'm being over paranoid! about what probably is also common on these beasts.
Could be the differential ... nearly all differentials (in all makes) whine from barely perceptible to loud. Most, however, are never heard above the interior noise and through the insulation. And, often they are noisy at just a certain speed, or under acceleration or under deceleration at certain speeds.