My wife does 12,500 miles annually which is entirely urban short distances (community nurse).

I would like to get her a car which would cost me ideally as little as possible to run, but be a decent car otherwise.

My options are a low mileage (<40k miles) used 06-08 reg small car (approx £12k over 4years total cost) or alternatively a new KIA Rio 1.1 CRDI Ecodynamics (88mpg) which will cost more over 5 years (£14k) but actual running costs (fuel/insurance/MOT) and finance will be less per month.

Furthermore, I wonder if a diesel car is likely to give a saving in this context? I would aim to keep the car at least 5 years.