Take a passenger with you and have them sit close to the noise and see if they can push or pull something that affects the noise.
I did that with my Y and passenger located inside the front vent rattled. Mobile service took it apart and was done in 30 mins. Maybe you will get lucky and be able to DIY or find some way to stop it temporarily.
Yes, it turned out to be in the area of the lift gate hinge. If you apply pressure to the trip trim piece, the creak is there. I also heard it when opening or closing. I took it upon myself and relief the gaps of the panels a slight bit. But what really did it is loosening and retightening the bolt to the antenna amp, which relief the stress between the pieces.
I have had my Model Y now for 4 days and I too have rattling in the cargo/trunk area. My husband just got his Model y 1 1/2 months ago, and he has not issues. I will have to ride back there and figure out where the noise is coming from.
I hate to post another rattling issue, but since they seem to come up a lot, I was wondering if anyone could help me identify the cause of some rattling coming from the lift gate. I've included a 15 second video where you can hear it pretty clearly.
From other threads, I've heard of people adjusting the rubber stoppers, padding their license plate (I did this and it was definitely not the issue), looking at their subwoofer/amplifyer assembly, etc.
I'm hoping to try out a few fixes, but I may just create a SC appointment. The noise is fairly loud and had been happening since delivery in mid November of this year. To be honest, it puts a huge damper on the whole driving experience of this car.
A friend of mine got their Y a couple weeks ago and told me they had a rattle coming from the back. Not sure if its the same one, didnt press them on it since its a new car and I didnt want to pry. They set up a service appointment.
I'm sure they'll fix it... so much for improved QC at the factory. One day they'll learn it costs them more in the long run to fix this stuff post delivery.