hmmm....
i have a 330d remapped and at first i thought great on everything, although i have been stuck on short trips recently causing the mpg to step right down to 25mpg!!!
give it a boot and down the motorway and it'll float back up to 40mpg.
worried about high mileage???? in these modern times with good servicing and care i don't think you have to worry so much. the only issues i've got with mine are a couple of suspension links that have been replaced, thermostat stuck open and dpf got a bit clogged, but cleared up without any cost.

oh yes, mine is just tipped over 170k and is a dream to drive, auto is a must so a map can be applied without endangering your gearbox. that said, if economy is very important, i'd be considering a 2.0TDI, 200bhp is easy and more, much better on juice.

that's what the wife will be getting early next year to replace the bora, which has been very good over the years.