Every so often, every 1 out of 3 times the car is driven, there is a noise in the trunk area/behind the passenger seat. It sounds like there is a tree branch stuck in the right rear rim and it rubs the trunk well when you start rolling. The more revs the wheel, or driveshaft, or whatever it is makes, the faster the noise happens. Then it goes away and only happens when the car is cool.

Isn't this bizarre?

 

Is it a metalic sound ?

 

Did you put your kids in the trunk while you went to work, and forgot?

 

Nice username Mr Lomax hahha that was a classic movie

 

I have a damn good idea what that is. I was experiencing the same thing on my Civic. When the car was cool I heard a clunking noise coming out of the tire well behind me. Once hot the noise disappeared. It was driving nuts. It ended up being a glob of road tar that I had rode through. When the stuff was hot and I parked it would flaten out on the ground and cool and harden. Then when I left work or had started the car after the night that clunk came up again. It was hitting the floor pan on every rotation. And I had looked to see if something was there. It wasnt until I put the car on the lift at a friends shop that I saw the problem. Cleaning it off was a bitch. Have you noticed a vibration a high speed? I that was in my car until the remaining bits wore themselves out of the trend.
Hope this helps.

 

First, kids.....never

Second, why thank you. I'm glad you picked up on the name.

Road tar? Not sure, could be. Its not a metallic sound. It's like someone is hitting the panel behind the passenger seat with a mallet and it gets faster as the wheel spins faster. I'll have to climb under there and see whats going on.