My 2001 E320 wagon (120k) eats bulbs (tail light, brake light, driving light) constantly - has since ~ 35k. Dealer got sick of seeing my wife when she came in for replacements, but never was able to find the root cause.

Power seats needed "rewiring," COMAND unit replaced 3 times, CD changer replaced, climate control brain replaced 3 times, Timeport brain replaced 2 times.

Other than now needing a new harmonic balancer (more info and photo here), its been solid.