Thanks everyone. I very much appreciate the comments and now have a sensible conclusion:
I must have parked, left, locked and walked away leaving the car running with about 1/4 tank of gas. Somehow the flashers were going as well. And my security patrols did not notice or decided to inform me of this situation. This drained the gas and the battery.
Further,
intentional vehicle design allows the car to be left running:
- in park
- while locked
- no one in driver's seat to trip seatbelt warning
- FOB out of range
2 design benefits are:
- safety [e.g. FOB battery dies while driving making FOB look out of range] or
- convenience to deliberately leave car running while locked and FOB out of range - [e.g. warming up the vehicle]
Under these circumstances, I am the negligent party therefore not qualifying for BMW warranty action.
I very much appreciate this forum and everyone's help. I feel for those with similar circumstances without the ability to discuss their situation with other enthusiasts.
I hope this thread has enough term triggers for others to find if they have similar questions.
Bob.