A guy on a 3 series forum let his girlfriend take his car to work and left the car running for 9 hours! Something about not understanding how to use the Comfort Access keys.

Idling for a couple hours is not going to hurt anything except your fuel mileage.

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2004 (05/04 build) X5 4.4i - Silver/Black - Premium Package, Sport PAckage, Rear Climate Package, 19" Wheels, Navigation, Park Distance Control