The dealer won't go through nearly the effort posted here in the DIY. They will put some foam here and there to fix a problem temporarily but that's it -- that has been my experience anyway. For me they were even willing to look at it multiple times, but they just did more of the same each time.

In my car the rattling was not just an annoyance, it made the stereo unlistenable .. and we can't have that! So I went on a mission as well .. took out rear seats and then spent some time in the back while playing a CD with a lot of bass (if you have XM, that seems to reveal the problems more). At first I just poked and prodded around looking for spots where rattling occurred. I checked all around the back seats, rear shelf, even popped the trunk and took a hard look at the trunk lid shelf (or whatever you call it) -- that is the main place the dealer will fix rattles by placing thick foam squares in strategic positions like directly behind the sub. This is the area that you pull the clips out from under the trunk lid to access the wire for the brake light on the wing, etc.

In short, I had rattles coming from all over the place. This explained why the dealer would fix one and another would then pop up - they are freaking all over the place in the rear of the car. I can't tell you how much felt and foam (pipe insualtion) I rammed all over the place to cure the ills. The key thing to do is once you get it all apart, spend some time tapping and listening to a whole bunch of areas wherever you notice a rattle .. and even where you don't. I found that places that did not currently rattle, would rattle with the slightest tapping on a part/shelf. The worst source of rattling for me was where the side of the car met the rear shelf .. that rattles something fierce when it does. Easy to cram some pipe insulation in there to fix. You can do that without removing anything.

That rattling by the seat belt holders may not be from there incidentally. I took a hard look at those but eventually I found by putting foam/felt in a lot of other places it didn't rattle there anymore. What you need to do is find the areas where plastic lays on top of plastic or metal and that is where you need to put your foam (larger gaps) and felt (narrower gaps).

This was a fair amount of work/time but it was worth it, I have not had any issues since I made this effort. The DIY above is a great start and shows you how to access everything. I did not take out the rear parcel shelf but it would have been a lot easier to access everything if I did. However if you do that, you kind of lose the ability to tap around and isolate where the rattles are coming from. So depending on your issues you may or may not be better off taking off that rear shelf. I found that cramming pipe insulation under the rear shelf (not easy to do because of access from under the trunk lid) toward the rearmost part of the car helped a lot -- I think at times the vibration from the sub causes the rear of the shelf to vibrate against the window. That's my theory anyway.

I've had my car 5 years and I still absolutely love it - and I sure hope Infiniti did a LOT better job on this in later models of the G. In almost every instance of fixing a rattle (and there were a TON of places) you could look at it and say 'yeah, that's gonna rattle'.

Good luck to all!

 

I would like to thank all those who posted their problems and fixes on this website. The information has been invaluable in my quest to fix my rattle problem. Therefore, I want to return the favor by posting my story of locating and eventual remedy of an elusive and intrusive rattle in the rear parcel shelf area.
For over a year I had an elusive metallic rattle or click in the right rear parcel shelf area. I finally concluded that the rattle only occurred when the weather is cold. During the summer months I did not detect the rattle but now since it is fall, the rattle returned. Originally, I thought the problem was in the area of the right rear shock tower which can be accessed behind the rear seat back by pulling up the fabric cover attach by Velcro. I thought the shock absorber might be the problem – so I replaced them. The intermittent rattle/click continued. I then turned my focus to the rear parcel shelf. I use foam pieces to stuff the various cavities –the intermittent rattle continued. I then turned my attention to the seatbelt retractors – my various attempts did not stop the problem. Finally using some of the post from this website, I removed the rear parcel shelf finisher and Dynamatted (actually I used GTMAT) the entire rear shelf area including the shock towers. This substantially quieted the rear shelf area – why didn’t I do this earlier?
For good measure I left the rear seats out of the car for a week to verify that I had indeed fixed the problem. On one of the cold mornings backing out of the garage the dreaded rattle/click happened. As I drove down the street – it was there again. Having another person drive the car – I tried to isolate the area the rattle was emanating – back to the right rear shock tower again! On the weekend, quite by happenstance, I found the problem.

(see photo)There are multiple spot welds in this area joining several layers of sheet metal.
By pressing on the bottom piece of sheet metal – it would “oil can” (a term used by sheet metal workers meaning it clicks like the small metal clickers we had as kids), behind and to the left of where these two sheets meet.

I am not sure if this is an anomaly but since I have seen other post of similar noise – I may not be alone. I remedied the problem taking a straight screw driver and slightly prying apart the two sheet metal pieces and injecting epoxy. Then I went behind the joint (through the trunk) and injected the area with urethane adhesive sealant.
It has been two days since the fix and no rattle or click – my over 1 year search hopefully it over.
This is obviously a problem that no dealer would have taken the time to find and because of the intermittent nature of this noise – I did not even try. The metal would expand when it was warm thus not clicking but when it was cold – click/rattle away.
It is too bad that I finally fixed the problem just as I am getting ready to sell it and buy a new BMW.
I hope this helps someone with a similar problem.

It has now been a couple of months - the problem is fixed!