I had this same concern not long ago...

http://www.peachparts.com/shopforum/showthread.php?threadid=22867


Since I've started doing my own, I'm averaging 15K between front sets on the W124. And my daily commute is a mix of city/hwy...

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2009 ML350 (106K) - Family vehicle
2001 CLK430 Cabriolet (80K) - Wife's car
2005 BMW 645CI (138K) - My daily driver
2016 Mustang (32K) - Daughter's car