I've had several friends who have put over 200k miles on their BMWs with no problems... Those were mostly E34 5 series and E36 3 series cars but at least it gives some bench mark that the typical BMW motor should go strong for a long time.

__________________
Current Cars:

2008 X5 4.8i - Blk/Saddle
2001 330Ci - Titanium/Black Sport/Premium

Past Cars:
1993 325is Blk/Blk Sport
1995 M3 Blk/Blk
1997 328iC Blk/Blk Sport/Premium
1998 M3 Silver/Black
2001 M5 /Black/Black/Sport
2005 X5 3.0i - Blk/Blk Sport/Premium