Hello all! I am still fairly new to the whole mini scene and so I am getting used to all of the little things the car has going on that are considered normal.

I have attached a sound clip that I hope works for you (I am using windows 8.1 think). The sound is coming from the rear of the car. Specifically the back passenger almost next to the wheel well. all i have to say is wow, that was a PIA trying to upload an audio file

The car is off and in the garage. The knocking sound I take it is from the exhaust system cooling down.

 

Can you get a better location of the sound, it might be the evap system after the car cools down or the leak detection pump.

Right before start up and you open the door on the Cooper S and JCW the fuel pump will prime in the back and make a short buzz noise.

 

Thanks! Yes I am familiar with that sound your talking about and that sounds like it comes from the back driver side near the wheel well. That sound will even happen when you unlock the car with the remote I noticed. This sound that I am playing I never heard before but that is probably because I haven't' had the car long. It also doesn't make the sound every time.
I will try to expand on the specifics of the location:
- under the car obviously
- back passenger side location.
- Specifically speaking I laid my phone down on the ground just to the right of the back passenger wheel just beyond where the jack pucks are located to support the car on jack stands.
- I think I see part of the gas tank there actually with some support straps around it. But again, i never heard this sound coming from that area before.

The car is a 2011 MCS R57. Specifically this car has the N18 engine. I state that because I know that engine has its subtle differences from the others.

Hope this helps!