I don't believe the latest diesels are any more efficient than the slightly older ones. Wasn't the galaxy available with the VW 1.9 Pd engine? It's a bit clattery at idle and gruff under hard load but it's as efficient as anything else.

47mpg will be hard to achieve with anything that size, but it is achievable depending on how it is driven.

Heavens knows what the reliability will be like, but plenty of Renault Grand Scenics seem to go for not more than £4k (1.5Dci or 1.9) once they hit 5/6 years of age. Likewise, plenty of last generation (or more recent high mileage) Zafira's, which according to real life figues on here , will just about hit your cost/MPG target.

There must be a few tidy Citroen Berlingo's out there for that sort of money, with the optional 7-seat Family Pack. The 1.6HDI engine, with the 150,000 mile cambelt change intervals, is the one to seek out.

Also check out Renault Kangoo, Fiat Doblo.

If you need the room, I agree wuth Unthrottled: go for a Galaxy / Sharan / Alhambra with the 1.9 TDI engine.

If you don't need something as big as that, look at a diesel Toyota Verso.