With all the differences of opinions and recommendations, I decided to let my German dealer decide which oil to use. They recommended 5w-30 and used Castrol Extended Performance specifically. They also said "no way" to 0W-20 when I mentioned the recommendations in the manual for the same reasons others have cited. I feel good about sticking with 5w-30 going forward.
I don't know if it was in my mind or what, but after the oil change I felt like the car was noticeably more responsive in the low end while in Comfort mode. I thought I had accidentally switched to Sport mode without realizing, but I hadn't. Again, could just be placebo effect. IDK.
