Considering a Cooper SD - any advice?

Firstly hello, first post on here...

Considering a 2016 Clubman Cooper SD and was wondering what everyone's thoughts in particular on the engine are.
How reliable are they given that anything of that age will now be out of warranty? (I've had a few older diesels - pre 2004 - but have a bit of a fear of these new ones!)
To be fair it will have a fairly easy life doing my 40mile return steady motorway commute every day and I'm too old and boring to be ragging it about much these days but I do want some piece of mind that it's a solid engine.
Also what kind of mpg can I expect in the real world (again steady motorway use). I'm currently getting a real 50mpg out of my 1.4tsi Octavia so not really wanting my fuel costs to increase given that diesel is more at the pump.

I realise all the above sounds like I don't really need the 'S' version, and I guess that's true but If I don't go for the one I really want then I might as well stick with what I've got as I can't really fault it as a means of transportation - it's just that I want something I can love and enjoy!

A year back I had one of those 48hr test drives in a Clubman Cooper S (petrol auto, but if I was getting one it would be a manual) and loved it, how does the diesel compare for every day driving?

Sorry that's a barrage of questions, I bow to your superior knowledge!