So, for the past about 7 months, I've been having this annoying tapping noise from the rear of the car whenever I go over speed bumps or washboard surfaces. I thought the noise was coming from the interior from the rear passenger side. Today, I took apart half of the interior looking for it. I removed the passenger seat, the center console, the passenger side 3/4 panel, the rear seats, and the passenger carpet (and confirmed there's no rust there). One of the plastic clip holders for the passenger side 3/4 panel had de-bonded from the panel. I Jb-welded the plastic and let it cure. I thought that was the source of my problem and re-assembled the interior. I also checked my trunk and there was nothing loose or banging around back there. Not even in the area of the spare tire. I went out for a drive hoping I had solved the issue, but no. It immediately presented itself.

At this point, I would have to disassemble the driver's side as well and remove the headliner to see if I can find the problem. I will try to convince my sister to ride in the back with a stethoscope (will a medical one work?) to see if she can locate the sound. There's also the possibility that the sound is coming from outside the car?

Whatever it is, it is very annoying. Here are a couple of videos I took while driving where you can hear the noise. Hopefully, someone has been through this before and can point me in the right direction.
You might need headphones.

 

I had an annoying rattle coming from the rear end on rough roads and it was the muffler banging around due to a broken muffler mount. I could hear it inside the car and I couldn't reproduce the sound by hand but while trying to find the rattle I noticed the snapped rubber mount. I replaced the mount and the noise disappeared.

 

Huh, that's something I never thought to check. Thanks for the suggestion. I will let you know what I find.

 

I had an annoying tapping noise and found it was the hand/emergency brake. Check if the cables are taut and see if the cable's U splitter is bouncing around, or maybe the fittings inside the drum brakes.

Also check the steel lines under the car which are held in place by plastic clips to the underbody and they are known to degrade over time and break.

 

Also check whether your high mounted rear brake light is mounted firmly to the rear screen

 

Before the oil cooler line incident, I had removed the high-mounted rear brake light and found no improvement. I also drove up the driveway in reverse (it's on a slope) and checked the steel lines and everything was good there. No clips were missing. I also checked the exhaust. The right side exhaust is tight with no movement, the left side makes a small squeak when you jiggle it, but not a tap. I checked the park brake cables and everything was taught there. I couldn't reproduce the sound.

So now I was back to suspecting the interior.

And then the oil cooler lines incident happened. When I removed the oil cooler lines today, I lifted the car via the front cross member under the radiator and placed jack stands on the front side sill lift points. As I was lifting the car I heard the tap. It was a single tap that sounded like if something made of metal hit something else made of metal, neither of which sounded like it would be hollow. The front wheels had already been off the ground when I heard the tap. The tap seemed to originate from the rear or mid-section of the car.

After I am done with the oil-cooler lines, I am going to check for any loose suspension components or bolts in the rear. Any other things I should check back there?

 

I had this problem, it was loose and rattling all the damn time. Someone had pulled it off for some reason.