Finally found it. Creaking / plastic rattle noise in the rear. As suggested earlier I took off the top cover to the rear spoiler - a handfull of Torx screws. What I found was the rubber tubing to the rear window washer was just the right length so that it draped inside the spoiler so that it was just touching the lower panel. Over small bumps it was basically 'tapping' on the plastic lower panel. A loop of double sided tape around the tubing so that it sticks to the lower panel and no more noise! Happy!!!!!!!!

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