As for high mileage, it depends on the age of the car I reckon. For example... If it's 5 years old and done 120k miles you can pretty much guarantee that it's a rep mobile and it's mostly been motorway miles which quite frankly is nothing. On top of that it'll probably have been serviced undr company expenses so things will been done on time under a lease agreement.
If however the car is 10 years old and done 40k miles I would stay clear because it's probably just been driven to and from the train station all week and never really got up to temperature. That's why I would never buy a old low mileage bike with 'only dry miles' in the ad. Rubber seals/bushes rot after time if there's no heat put through them.
As long as stuff gets done on time and when it needs doing, there's no reason a modern engine shouldn't last 300k miles. Mate of mine had a 225k mile Vectra before the head gasget went, and he was a nutter.
My BMW 535 had done 120k miles and on the last service I did we pressure tested the V8 and it was at 98% across the board. As long as you keep changing the oil the engine should be fine. I reckon you want to be looking at the affects of weather more. Look at the underneath of the car, wheel arches, etc, and defo pay a lot of atention to the radiator.
don't I?
had a little 1.4 engine what pulled it down the road really well, can pick them up for a cuple of hundered now as well (still fugly as a cats anus tho)
