 I purchased my 03 A6 3.0 certified pre-owned with just over 36k miles.  It has been without question the worst car I've ever owned.  3x stranded roadside and counting.  Numerous major repair items not covered by warranty. V-belt failed 15,000 miles before scheduled to be replaced, caused auto tensioner to seize and break ($2,500) not covered by warranty.  Motor mounts failed ($600) not covered.  Carbon deposits in throttle body cause SEVERE vibration. (proposed repair well over 2) Fake wood dashboard pieces have popped off and will not stay on.  I follow maintenance schedule to a T including $80 full synthetic oil changes, engine idles like an old pickup 2,500 miles into a 10k mile oil change.