Update: second BMW mechanic cannot find the source of the battery draw. X5 goes to sleep as it should. He's noticed the instrument panel gauges come on randomly -- temp gauge, etc. Has found some computer error codes relating to the instrument cluster, so believes the cluster needs to be replaced. BMW charges $1,600 for the part! So, $2,000 out the door, but with no guarantee it solves the problem. I'm walking away -- and maybe time to sell. It's been over a month, and two mechanics, with no clear solution.