How about this noise coming from the heater fan? The natural flex of the body, especially in a turn, could sometimes cause the squirrel-cage fan to touch on one edge.
I doubt body flex is causing that. I thnk it is a foreign object that may pitching slightly, or bad bearings in the blower motor itself allowing the squirrel cage to shift.
It’s probably the fan motor bearing. I find that particularly annoying. The cure is to replace the blower motor.
I do not know about the cricket… my brother bought a brand new Passat, after several visits to the dealer and the cricket is still there. I am writing about the plastic burn smell that Sam mentioned towards the end. I had an A6 2000, the smell is not plastic burning but most probably oil. A gasket at the rear of the engine was leaking and the oil dripped on the exhaust…At every stop fumes were coming in through the vents.
Could be that something got dropped in the plenum when the cabin air filter was changed . My Passat had a leaf in there till the fan finally digested it !
I think this is something in the heater fan, too. As I note below, caller should experiment and try to turn climate control fan to a manual speed, or completely off.
From 1999-2006, I had a 1988 MBZ 560SEL with a similar issue, that also only happened occasionally, and only in cold weather. If the climate control system was in fully automatic mode, it would run the fan at variable speeds. Sometimes it ran at a speed slower than the manual low setting. I assume the engineers wanted some air movement, but with minimal cabin noise.
I would have replaced it, except that the service guy assured me the job took MANY hours of labor. I got the impression that the fan was buried deep behind a lot of other stuff.
When the cricket noise occurred, I could get rid of it by forcing the blower to any speed. Usually, after 30 seconds, I could switch back to full-auto mode and the noise would be gone. The most common occurrence was in the last half-mile of my commute home, when I am making more turns. But it happened at other times, even on interstate highways.
My brother in law had an early 2000s Audit A6 Avant wagon, and it had the same problem. We joked that MBZ and Audi were buying the fans from the same vendor.
The caller was able to step out of the car and hear the noise from outside the car, so it doesn’t seem likely to me that it an exhaust hanger; I think that kind of thing happens more frequently when you are moving and the exhaust if flexing more than it would at idle.