Follow up note on this from today's drive. So, went to lunch. When I went to leave (and forgot to pre-cool), the revving starts up as normal. Once I got the family loaded into the car (about 2 min), the revving was still going. As I start to drive off, I notice the revving goes away. But I had to stop at a red light within a minute, and the revving started back up. Then I drove off at green, and the revving stopped. Got stopped again a minute later, and the revving started up. Then it went away.
So, again, I accept this as all normal and expected. I guess since I've driven a Volt for over a year in the heat, I'm used to the compressor sounds (for AC) and other sounds (for battery thermal mgmt system), esp on startup. But I found that it was interesting that once I press on the accelerator, the revving stops and only resumes when again I stop. So, I'm wondering if the revving is some sort of generator drawing the energy to work the AC when there is no draw from the motor.
I'll also repeat as I said in my prior posts, there's no vibration in the steering column at all. And I guess there's gonna be some very low amount of vibration somewhere, but its not felt. If you could block out the sound completely, I wouldn't really know its running.
And all that said, I will say that the AC in the MS runs circles around the Volt's. Its cooler, quieter, and much more efficient.