My '17 800 Z force starts to make a whine at 30 KMH, not objectionable but present. It seems to fade away into the other mechanical noises from 60 Km onwards.
I always chalked it up to the driveline parts reaching a certain harmonic. It's been doing that for 10500 Km now (since new) and doesn't seem to be anything more than just a phenomenon of the machine. We'll see I suppose. When I think of it as the supercharger in Mad Max's pursuit car, it doesn't bother me.