Wondering if anybody else has seen this too — well, heard it, actually: Over the past couple months or so, on my 2017 ‘Prime Advanced, with 66,741 miles, as I accelerate through 57MPH, at around 54MPH, I start hearing a … hum? As my speed increases, it peaks at around 57MPH, and then trails off, until at 60MPH or so, it’s pretty quiet again. Observed qualities: — Even at its 57MPH peak, it’s not overbearingly loud, but only slightly annoying. — It’s much quieter in hybrid mode than in EV mode, so it’s presumably some sort of resonance in the electric drive train. — It’s probably pitched at roughly the Eb above middle-C on the piano. — Its probably fairly sinusoidal-ish. Anybody heard anything like that?
Tires would be my first guess; they can change noise with wear. Being louder in EV could just mean the engine noise covers some of the sound up.
Reasonable question, but no, definitely not tires: When I ease off the accelerator so as to hold at 57MPH, rather than accelerate through 57MPH, the volume of the sound goes down. Also, as I mentioned, it’s quieter at the same speeds in hybrid mode than in EV mode. It seems to be related to how much power the MGs are producing in the speed range.
