I have about 15K on my 2020 G550 and the rear brakes have squeaked pretty much since I've had it (bought preowned with about 9K on it). On a chance I order a set of rear brakes made by dynamic friction (???) and were like $30, so I figured I mine as well try it out and see if it makes a difference. The pads plus Wurth anti-squeel spray seem to have done the trick. Been about 2 weeks and hasn't made any sounds at all. A little less brake dust than up front and there is no noticable difference in the braking performance (though it is the rear pads). So much better now without a noise when I tap on the brake lightly!
https://www.rockauto.com/en/moreinfo...t=1684&jsn=898
Second, I've also had vibration noises coming out of the door panels at random times driving the car (lots of well documented use cases) - I found a great youtube video that shows how to take to door panels off
And behind each panel I put
material on all the parts of the door where you could and then on the edge of the door where it touches metal, I used the thinnest weatherstrip I could buy (sticky on one side) and put it on the door panel itself.
After doing this, the car now is dead quiet with no interior noises!
Its all pretty quick stuff to do, and cheap at the end of the day! For my car it made a huge difference, so I thought I would share!