When I had my MINI interior out for sound deadening (prior to my custom RSD project), I noticed the rear sill cover has a vent across the front of it, with a foam "filter" behind it. (My filter was covered in dog fur). The sill cover goes over a hollow beam with two oval shaped holes in it.

Is this some type of passive ventilation? Air pressure relief? The vent actually lets quite a bit of noise in from the rear of the car (squeaks from wheel wells, bumper skin and if your spare is not attached perfectly, the spare tire. I slid a piece of close-cell foam into the slot and it cuts out quite a bit of noise -- just wondering if there will be side effects (window fogging, air pressure, etc.).

This may only apply to Justas, not sure about MCS. Thanks.

 

I believe it's for air pressure relief when closing the hatch

 

Can you post a pic of the vent? Thanks

 

It serves two purposes; pressure relief when closing the boot and passive flow through ventilation while driving around

 

Here you go. Sorry for the dog fur/dirt. It's not the full back, but you get the idea. On the right you can see my rear-seat-BELT-delete cover (first prototype).



The metal under the sill cover looks like this (see part number 3 in the diagram below):

 

The vents have been there ever since the beginning (1st gen). As mentioned, they are for ventilation and pressure relief. The topic has come up before and people have said that the AC doesn't work as well when the vents are blocked.