Just out of curiosity, have any of you noticed a 'rattle' in the back seat rear compartment area?
My 2 door F66 has developed this within the last couple of months, or longer, and I can't seem to trace it down.
It sounds like a loose wiring harness banging inside a plastic side panel.
It happens if I hit a bump or drive on a rough road....

I removed all the items in the rear compartment 'trunk area', put the rear seats in the up and down position, checked for anything loose or not bolted down properly, made sure the rear seats belts weren’t banging against something… no luck at all.
I thought the rear license plate holder might be the cause... nope.
I also checked the 2 small access covers on the sides in the trunk area. Couldn't see anything loose inside.

I have taken this car on some rough dirt roads in the past, so maybe one of these jaunts might have loosened something underneath... a heat shield, muffler hanger, or?
After raising the vehicle, I could see nothing that was obvious.

I really don't think it is anything serious, like a tire falling off, but it does bother me and wasn’t there when I bought the car….

 

Ironically I thought this was just the extra crap I threw in that little compartment area inside the rear hatch area. Perhaps it's not that, after all.

 

Yeah, I was thinking the same thing at first, but after removing all the 'stuff' from the rear compartment, even the hatch compartment cover, it's still there.

There is a plastic surround attached to the rear inside hatch (around the rear window). This has a wiring harness inside for the rear brake.
Not sure this is the source of the noise, but I figured... what the heck, I would remove it and take a look.

There are several attaching screws, but after removing them, the trim wouldn't come off.
Apparently, there is some trick to this, though I haven't figured out what...

This almost sounds like the rear seat isn't bolted down properly, but I can't move the seats.

Not sure I want to take it to the dealer, as they are quite a distance, nor do I know if they would have any better luck at finding the source of the noise, unless they have run across it before.

If I do, I'll let everyone know what they say.....

 

Yep, I'm in a bit of the same situation where I'm not close to a dealer (about an hour drive), and it's a noise that only happens very infrequently and not consistently. I'm afraid if I do take the stuff out and it's still doing it, and I do take it to a dealer, they may poke and prod the car and end up creating another noise elsewhere haha. So I've just accepted that it is what it is and I try to avoid potholes and the such anyway!

 

BULLPUP01, I am not sure, but, if the rear seat bottom is attached the same way as in the F56, it is just clipped in, a good forceful yank of the front edge of the seat bottom upwards and it will be loose in your hands.
BTW, I have not noticed any unusual noises in my 2026 F66 JCW

 

PClay...

Great idea... once the weather settles down and the garage isn’t an icebox, I’ll give your suggestion a try.
There could very well be something loose under the seat.

The noise is frequent enough that it’s getting on my nerves.
It definitely wasn’t there when I bought the Cooper last summer, and the fact that it’s developed over the past few months tells me something has worked itself loose somewhere.

Otherwise, love this fast and fun little Mini!

 

Okay... nice weather today, and had some spare time, so I pulled everything out of the back of the Cooper again, intent on locating the source of this very bothersome noise.

PClay you were right.... a tug upwards on the front of the rear seat and it popped out easily.

My Cooper was a loaner before my purchase... just a couple of thousand miles on it, but there were some pistachios and other stuff under the rear seat... really?
Vacuumed it all out and inspected the side panels, etc. for anything that might be loose and causing this banging noise. Once again, nothing obvious.
Tightened anything and everything I thought might be an issue.

Took a spin with the back seat removed and everything still out of the back.
80% better (I think)... not nearly as much noise when hitting bumps and rough roads... interesting.

Reinstalled everything and it does seem to be better than it was.

One other thing I did... the rear license plate in its frame is 'loose' on the attachment plate on the car. I took a piece of closed cell foam and cut it to fit between the plate and frame.
No noise or play from that bad boy now!

Will check this over the next few days and report back as to whether this resolved the problem....

 

Cool