WARNING: This page is about a different car, the 2008 BMW 750i, 2007 BMW 750i, and 2006 BMW 750i. However, it is still accessible from the selected car via links, so may be relevant.
TIGHTENING TORQUE SPECIFICATION - ELECTRIC AUXILIARY HEATER
Type
Thread
Tightening specification
Measure
1AZ Battery positive and negative leads to auxiliary heater