"High mileage" is a description often applied to automobiles. From that phrase we can infer a number of possibilities:
- It's covered a lot of country, could be mostly in one county, but perhaps all over the continent.
- Might have a few dings in it, or some unattractive idiosyncrasies.
- Hard to discern the maintenance and care schedule; buy at your own risk.
- Maybe one caretaker, maybe driven by a bunch of folks.
- The "inside" -- engine and systems -- may have been carefully maintained, or not.
- The "outside" -- exterior -- may have been protected and cared for meticulously, or painted over repeatedly, or completely ignored.