average mileage life of mazda 3?

hey, i currently own a 03 protege. but im looking around for a mazda 3. the mileage what i'm worried about. i don't know the average life of a normal use of mazda 3. such as when does the transmission/engine or whatever start having major problems. going for a manual, the one im looking at is a 2005 model at 70k miles....and is there any problems i should be aware of and check for while test driving?
 
For problems, theres a TSB(technical Service Board) listing for problems that occur from the factory that thread is here. As for the average life, its still a pretty early to tell for their life expectency, but the mileage you said seems pretty average. i have 35K miles on mine and its an 06
 
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