Ive decided to sell both my cars and get just the one, mainly because I barely drive these days and fancy getting one 'better' car....

Anyway I will have a budget of around 15k and was going to bite the bullet and get a Range Rover Sport (diesel one). However having seen the prices of E60 M5's etc I'm reeeally tempted to get one. I'm aware that they aren't the cheapest to run or maintain but with the mileage I do its fine. What i'd like to know is am I better getting one with slightly higher mileage (60k+) that has had things like clutch etc already replaced or get the lowest mileage one I can find? Also what do they fail on and what is the general fuel consumption like? (I'm presuming mid teens?). The only driving I really do is a 100 mile round trip to the missus' (all dual carriageway!)

Thanks!