Vehicle noise interior at higher speeds

New D300 is developing strange noises in the interior when travelling at around 180/190+ kph. The noise almost sounds like "interference" from the sound system, i.e. it's an electronic noise rather than mechanical. I only have the standard differential (the manual specifies that anything above 190 kph is not recommended if you have a rear diff). Perhaps it just doesn't like German motorways.

Anyone else?

 

Could it be the speed limiter? From a quick google search the top speed is 130mph (210 kmh).

 

Good point, I might have to check. It starts at about 185 km/h, which is a bit annoying.

By the way, LR responded too...just in case anyone else is having a "noise issue" (this could be an entirely different noise, of course) >> There is a service notice about strange motor noises in the program that our dealers and we are using with the code SSM75266 - AJ20-D4, AJ21-D4,