Our 2004 120bhp 1.9dci with 22,500 miles on the clock averages approx 49mpg.
This is a mixture of driving,minor roads,A & B roads, and town driving - usually in heavy traffic- an 18 mile journey to work .I do not have a heavy right foot and never exceed speed limits on non-dual carriageway roads but I am not exactlly light footed either.
Even on holiday with a roof box and 1 bike on the roof and 3 bikes on the back we averaged 43mpg over approx 1000 miles, 700 of which with the car fully loaded with the above and coming back we also had a load of wine to fit in the car as well.
I can easily get mid 50s mpg if I sit and cruise at 75mph.
I always seem to get a little less in the winter and put this down to the additives the
companies add to diesel to stop it "freezing" and the fact that the lights,heater,wipers etc seem to be permanantly on -all using up more "power" from the engine.