I only suggested antiphase noise cancellation since I can't recall having read a discussion on this board about it ... Can you point me to the thread?

There were a few good replies when I brought this up in August. "At length" was a huge overstatement, I thought there was more than that.

Even if you implemented this, then surely you want the level to be set relative to what the driver can hear at his hearing position

Yes, but what you want even more is no feedback (you gave some good examples why not), thus the suggestion to put the mike outside the vehicle and assume that the noise the driver can hear is a linear function of the noise outside.

Plus, if you boost volume in response to ambient noise levels, then what happens when you try to use the long-awaited VR?

You won't be able to use both at the same time. That's OK with me, I'm not terribly interested in VR (says he while donning his asbestos suit - flames are guaranteed to come when you utter such a heresy) so I might as well put the mike to good use.

Borislav