Concerning the Teflon Taping Procedure, Cars that are under BRSI very possibly, get it done for free. The tape in question is made by 3M Corp. and it's a Teflon Tape. In my case, the tape was applied to the areas where the Shadowline Rain channel comes in contact with the rubber and felt-lined seal. Look at the top of the car door, the section above the window of the door has an edging. On the outside(the side that you see when you close the door from the outside) it's rubber; on the inside, it's a felt material. The cracking or squeaky sounds that you hear are possibly the sound of the felt rubbing against the rain channel. Still with me......?
One of the tell-tale signs that tell you that you need to reapply car wax is to rub a dry microfibre against a clean and dry panel on the car. Basically, after washing and drying. If the microfibre cloth refuses to glide and catches and squeaks, it's a sign to wax your baby. Applying Teflon Tape is essentially placing a non-stick surface between two very different materials. Resistance is negated...hence no noise.
The Teflon Tape is effective but realistically, a temporary solution. Gradually, the tape and it's non-stick qualities degrade and the squeaks and creaks begin again. Remember how easy it was to perfectly fry an egg on a recently purchased Tefal Non-Stick pan?
Some of the members here claim that this noise is more apparent in M-Sport models due to the dark gloss shadowline. I don't know....
Some have gone as far as to have the doors re-torqued. Some have demanded that door-clips and seals be replaced. All without much success.
I have had the Teflon Tape adhered on my Shadowline at Auto Bavaria without any charges to myself as the car was only two months old....and within a few months, the creaks came back. This time Auto Bavaria personnel applied some wax or gel or solution. The name of which I barely recall, as my faith in their ability to resolve this issue has somewhat diminished.
Hayashijb seems to have found a pretty good and cost-effective albeit temporary remedy by applying leather lotion as and when...
People overseas look for Gummi-Pfledge(German for 'Rubber Care') and swear by it. Apparently, it was a BMW product that anyone could order but it was discontinued. I understand that Wurth also makes their version of Gummi-Pfledge called Wurth Rubber Care Stick. The second best thing is Silicon Spray. applied over the seals... Wurth, a brand from Germany, is one of the better ones.
I applied a coat over a month ago....so far so good. But I hope that someone who has read this and knows of a better solution, would be kind enough to share it with the rest of us here.