I believe it hits reserve after being on "0" for about 20 miles, it displays ---, and then you can still go about another 20 miles w/o it stuttering

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2006 BMW X5 4.8is Lemans Blue/Beige/Dark Maple
-Nav, Comfort Seats, Heated Steering Wheel,
Rear Airbags, AUX Input
2009 BMW M3 Space Grey/Black/Carbon
-all options