I have a mid-March build 85D (i.e. built within the first month or so of non-Performance Dual motor models) and the whirring noise is definitely more prominent than RWD models but I find it to be a very pleasant sound. It kind of sounds like a jet engine.
I have not experienced grinding or anything along those lines but that does not sound pleasant. :wink:
There are a few sounds the motor makes is normal operation -- a whirring, turbine-like sound (I think this is the original subject of this thread -- a few people had issues with the D as it was louder having a 2nd motor near the driver) and a balloon squeal under heavy acceleration.
There are two problematic drive unit sounds (these don't appear to be related to failure or loss of performance, but Tesla will replace drive units for these sounds). One is called the "milling sound" by Tesla. This buzzing sound starts at 10-20kW power draw around 18-25 mph, and gradually gets worse, expanding the upper bound of both power draw and speed. This sound gets quite loud and annoying if the drive unit is not replaced by the time it is happening up to 40-60kw draw. There is also something Tesla calls a "droning" sound. This occurs at freeway speeds and sounds kind of like an older 4 cylinder car struggling up a hill behind you. As far as I know these apply to the original, large drive units used in RWD vehicles, and the P85D/P90D cars. Whether these sounds will manifest in the new, small drive unit used in the 70D, 85D and P front unit is unknown.
This is supposedly what Toyota/Lexus use to cancel engine noise: Couldn't this be done as well for the MS? Tesla could update the algorithm over time which is a huge plus. I figure that noise cancel will be more effective vs an ICE car b/c the MS motor would produce a more reliable whirring noise vs an ICE engine.I have an S90D that I took delivery of on Monday -- built mid-September 2015. I don't find the sounds in my MS loud, something I'd complain about, or will likely be annoyed with. I come from having driven two different Lexus RX AWD Hybrids for the past 10 years, and my MS is even less intrusive in terms of engine/motor noise as long as the pano roof and windows are closed. (My Lexus RX450h was far quieter with it's moonroof open and/or a window down at speeds up to 50MPH or so.)