Here is a 10 minute video from our one hour test drive. I edited it down to get the squeak's 'greatest hits'.
After our drive earlier we went to Tom's house and started looking at possible causes. We removed all plastics from the hatch door and with it closed, he took an orbital buffer to the exterior and nothing major was audible. So we opened the hatch and he took the buffer to interior surfaces. We noticed an absolutely obnoxious rattle coming from the passenger side of the hatch door. I grabbed a hold of the damper while he applied pressure with the buffer and the rattle stopped.
The passenger side hatch damper had a lot of play in it, and the rubber bushing around the mount on the chassis seems to be worn because when I moved it there was a metal-on-metal clanking. There was also a clanking coming from the joint on the hatch door. I tried the same with the driver side hatch damper and it was much more solid on the chassis, but still had a clanking on the hatch door... however much less noticeable.
We removed both dampers and put them in his garage with the plastics from the hatch door and went for another drive. Hitting the same bump that causes the squeak to occur every day for me, yielded no squeak
this time... Hmm, I better do a u-turn and do that again just to be sure... nope, no squeak. Daww, OK once more for funsies... sweet, no squeak! I don't want to celebrate prematurely but it seems we may have found the cause.
Tomorrow, we're going to go on another plasticless-damperless-hatch-door drive while the car is cool (it's 110~ right now) to make sure the metals weren't just more pliable and not squeaking because it was warm. If it doesn't squeak, I'll be more optimistic.
I should note that it is likely we're on to something here, because when the service manager was diagnosing the issue he said that he got the squeak to stop by having one of his techs wedge a screw driver between the layers in the roof near the hatch
(see first pic in post #33
for reference). In order for his tech to do this, the hatch would have to be open, furthermore I'm sure they were holding it open if they were driving with someone in the hatch so it didn't close on him. This would relieve pressure from the damper, thus preventing the squeak. We'll see though, only time will tell where this goes.
I will say that we're going to get some adhesive foam & felt from Home Depot, or whatever artsy-fartsy store we have around here, to keep the plastic panels on the hatch door from rattling so much... they sound awful all on their own.
More updates will be posted as I have them.
BTW, thanks again Tom... your help is greatly appreciated, sir.