I just traded my 2007 Cooper (manual transmission) for a 2013 (automatic) in April. Whenever I back up the new car after it's been sitting for a while (whether parked overnight, all day at work, or for an hour at the mall) I hear a loud snapping or popping noise at the rear of the car. It sounds like some wound-up spring has suddenly let go and has snapped against a piece of metal. This always only happens in the first 5 feet or so of reversing, and only happens once, and never happened on my 2007.

The only things I can suspect are that either the parking brake is sticking and suddenly letting go, or something weird is going wrong in the transmission. Has anyone else heard this? I had asked at the dealership (this started a month ago) and although the mechanic tried the car out and heard nothing, he thought it might be the calipers sticking and then suddenly letting go but said it was nothing to worry about.

The noise seems to be getting louder over the past week and so I'm going to call the dealer again, but I'm wondering if anyone else has encountered this.

 

My guess would be its brake related as well. Does it only happen in reverse? If you were to go forward after being parked for a while, is the sound still there?

The way you're describing it kind of reminds me of the sound of minor rust on the rotors breaking free from the brake pads after being parking in the rain for a day.

I think you'll probably have to leave it with them overnight so they can experience the sound themselves to realize it's worth fixing. It definitely sounds like something that shouldn't be happening - especially on a brand new MINI!

 

My 2013 does the same thing every morning when I back out of my driveway :-/

 

I have a 12 MCS manual and mine made a "crackling" noise when I backed up and took off and hit slight bumps in the road...took to dealer and couldn't replicate but it never came back ever since...not sure if the crackling noise is same thing you are describing.

 

On my R56 I get the same thing. I is the brake pads moving a bit in the pocket.
They are normally jammed all the way forward for driving and braking. When you are in reverse and squeeze the brakes a little they move a bit. I have after market pads and they are not shimmed like the stockers so it is a bit louder.