Henry -- I know somone who has the last model TDi and it is incredible in terms of fuel economy. Really nicely built car.

Also have a look at the Peugeot 307 HDi. There will be a run-out of them in the next couple of months ahead of the new 308.

If you want something for fun, go the Renault Clio Sport. Great, affordable car that are a hoot to drive.