My 2005 G35 6MT sedan has a creaking / squeaking sound in rear deck, or behind the rear seats. Has anyone experienced this?

i have an 04 coupe and my rear deck sounds horrible i need to do something to fix it soon..

i have a similar problem but instead of the rear deck my small side window makes a tun of noise

The window is caused by the bolts in the window being too long. They'll replace these under warranty. If you are out of warranty, there is a service bulletin which shows how to do it. It's not too difficult.
As for the rear deck - I've found that in my car it is actually the structure behind the rear seats. I haven't yet taken the rear seats out, however, I understand that the bolts back there come loose and need to be tightened. When i do it I'll provide pictures.

i have a 04 sedan n have noticed a creek/vibration in the rear that is caused by the headliner hitting the rear window. maybe this is ur issue maybe not hope it helps

Thanks. I'll look into that as well.

I have the same problem with my headliner hitting the rear window. (Btw 04 coupe)

Annoys the crap out of me..... It began a while ago and got worse and worse.... First it did it when my subwoofer was hitting too hard... then started doing when my lightweight flywheel made my car vibrate a little more than normal due to low rpms... now even during regular driving it gets noisy sometimes...

I got fed up two days ago and stuck two of my business cards folded in half in the wedge btw the headliner and the window... it stopped but even though u cant really see the cards, in my head i still hate the ghetto fix...

Anyone else knows a better way? maybe sound mat or some kind of tape??

GL.. and for now if you need two of my business cards lemme know hah

expanding foam that comes in a can.....grab yourself a can of that and shoot it inbetween the headliner and the roof.....its what the dealers use to solve this issue when customers complain about it.

Uhh good idea, I'll swing by home depot on my way home.... if only I knew a home depot that also sold the famouns home depot nismo lip ahah... none of them seem to have it around here, and no manager has been able to help me find it...