Sorry petef, have to disagree with you there. Yes, they are less economical than a modern diesel but the depreciation has flattened out and depreciation will contribute far more to the total running costs of a car than fuel will.
For example my wife drives 12,000 miles a year in a Seat 1.9TDi, ave fuel consumption is 45mpg. I do the same annual mileage in my E320 coupe which averages 26mpg. Total cost of hers is £360 per month and total cost of mine is £230. For the purposes of this calculation I have depreciated hers by £3000 per year and mine by £500.
For me it's a no-brainer, I get to drive a nicer car with and a lot more character and pay less for the privilege!