Thanks Y5choi! I spent the best part of a couple of weekends adjusting the rear hatch and taking everything out of the back area, to see if I could find the crackling noise. The plastic spring loaded piece that slide over the rear lower hatch was the culprit. There is only a thin felt piece that seperates the two pieces. I laid a piece of foam insulating tape over the entire piece of felt and the noise is gone! I'll swap this with something more permanent as this was just an experiment to see if this was the problem. BMWNA, if you're reading, replacing this piece with a thicker insulator will save your customers much time and effort, and will save you $$$ by keeping the vehicle out of the dealer to fix under warranty!!!

__________________
E70 X5 3.0si Space Grey

E36 Z3 2.5i Roadster, Sterling Gray Metallic