See a lot of people commenting on diesels being unreliable over a 100k etc.
Lads, I've had mainly diesels over the years and some with 300k plus miles on them and they don't per definition give problems!
It's all about servicing... I would sooner buy a diesel with 140k miles on it which was serviced well (read better / more often than specified service schedule) than say a diesel that as done 40k miles in 7 years with only minimal servicing (I would consider the manufacturer service schedule to be minimal). E.g. VAG "long life servicing" will definitely absolutely kill your engine and indeed problems seen around 100k miles, but service it every 15k kms instead of the 20k (or 30k specified on some models for a short while) and it will happily do several hundred K without too much bother.
Another note on diesels... they are diesels and not petrols... and when you drive them like petrols, they will die quicker.
They are not made to "redline" and especially not on a regular basis - it kills them.
If you drive a diesel very little, or lots of short journeys, you will get expensive repairs like injectors, DPF clogged etc.
So be weary of diesels which lived in town and did small mileage for the years as for example a DPF will set you back big bucks.
Ireland, with its roadtax driven love for diesels, has a huge overhang of diesel cars with DPF, injector, EGR and valve carbon issues that are now starting to become systemic - Too many people who should have bought a petrol bought a diesel and then drove it around town for short journeys and are now getting landed with dear repair bills...