If you were buying a used vehicle in very good condition, what would be the maximum mileage you would accept before saying that the vehicle has too many miles for you to buy it?
200,000 miles is my max no matter how good a condition the vehicle is in. I would hope by that mileage they would have already changed the engine too.
It depends on the technology. A regular gas or propane engine is normally done by that many miles. A diesel is still good for another 100k or so. An electric would be good for twice that, of the battery still holds a good charge. Barring body damage for any tech typ, of course.
There are a lot of factors. Over a 100k is a risk but if the vehicle was well maintained and the undercarriage is all in order then all you might have to is an engine change at some point and you have a virtual 'new' vehicle.