How many miles is too much for a used BMW?

you must use your ears...and your nose...ears to hear if the valve tapping is minor and incidental and if there are any 'thunk' type sounds from a worn main bearing....also your nose smell the exhaust....is it laden with oil smoke...is it pre-dating Catalytic converters? you never indicated which year...but can tell you that if someone did NOT get their oil changes on schedule...premature wear will occur....and it's NOT your fault....the damage was done before you got the car....still which year would be the key here as the technologies have moved but swift....a used 2002 came into the shop, but was obviously 'in the shop' most of the time...nothing against 2002's they are sexy, but someone has not been adhering to the maintenance schedule....quite obviously~

...also an inspection of the interior----was it a "smoker's car" in other words is there a clear stinky film on all the exposed parts....was this used for pizza delivery...is there evidence of a Cigar being lit in the cigar lighter there? does the lighter work? do all the dashboard lights work? is the carpet stained, tattered or even present? are there rips in the seat front and back? does it track straight if you're lookin' down the side of the car...as if it has been in a major wreck?...are the tie rod ends loose and in need of replacement? are any of the fluids currently low? does the ethylene glycol in the radiator look reasonably transparent?~