One problem related to transmission failure has been reported for the 2009 BMW 650. The most recently reported issues are listed below.
I have a problem with the transmission of this vehicle, and it is dangerous. . . . Example is when I was at a stop sign for example, and I would accelerate to navigate the intersection the gear would jump into neutral for no reason, and leave me stuck in the intersection, any oncoming vehicle could have easily struck me, upon notifying BMW of this situation they diagnosed it as either a sensor or relay issue. It was corrected for a while. . . . The transmission again failed and this time they said it was out of warranty, the vehicle had 85,000 miles. . . . And was always maintained at a BMW dealership and was never abused in any way. BMW has also had a lot of issues with the engines on these models as I have.