I purchased a 2011 m56x a few months ago and have been noticing some strange behavior between 4th-7th gear when my foot goes near the throttle. For example, in traffic on the way to/from work I'll be coasting along around 40-50 mph and the revs sit around 1300 or so. when I go to accelerate and pick up speed again the revs jump up to around 2k and then immediately drop back down to 1300 or even lower and the car kinda glugs along with the same sound and feel as if you were in say a 6 speed accelerating from a stand still in 3rd gear instead of 1st.
It isn't the gearbox shifting between gears constantly because it happens also when in tiptronic and it only happens in 4th through 7th gear. 1st, 2nd, and 3rd go through the entire rev range without any hickups.
any ideas?
thank you for your input