One problem related to coolant leaking has been reported for the 2001 BMW X5. The most recently reported issues are listed below.
BMW X5 3. 0l 2001 1) car lost power on the freeway requiring an emergency stop. Very dangerous situation but no one was injured. 2) a hole in the plastic cooling system caused the coolant to eject. The engine overheated causing total loss of engine. There were no audible or visible warnings. Apparently this vehicle does not have a coolant sensor and the engine temperature gauge can malfunction if the coolant has all leaked out. 3) entire engine replacement at 63,000 miles (out of warranty). Car has had all BMW recommended maintenance service.