I had a chance to drive the 2011 535 and 550 today at lunch and wanted to post my reaction while it is still fresh.
First, the 5 series chassis is huge. The only reason I post that here is it had an effect on the butt dyno hauling so much more car around. The thing literally felt like the 740 I had many years ago. The size does give it a mongo mafia trunk big enough for two large adults
I drove the 535 first and I really feel sorry for those that end up with the N55 as opposed to the N54. The car was a real mutt. It felt more like a 28 then a 35. It was lacking down low, in the middle and up top compared to my 2010 535 when it was stock. I expected much more given the engine has what seems to be an infinite number of gears to work with.
The 550 was waiting when I pulled in with the 535 which allowed for a back to back comparison. Wow what a difference. I drove the new seven series several months back and had the same impression of the engine; it has good solid power delivery. I would guess that the car would easily out pull my 535 when it was stock and may just nip my car now with the calibration update. If the weight was the same, I think it would certainly out pull a tuned 535.
I did have one stomach in the throat moment on the on ramp at about 110. I stomped on the brakes reasonably hard to make sure I got down to a good merge speed and the car wallowed around like a pig. It felt like too much compliance in the suspension pickup points causing them to load up then release then load back up again. In fact, it felt just like trying to haul the old seven series down from triple digits in a hurry although I think the seven was more stable. Standing on the brakes at forty or so was perfectly normal and predictable. Doing so at real speed was anything but……
The ride setting was on Sport+ that seems to disable DSC but what I felt was not latteral load DSC stuff.