Maybe in the middle of a regen,as mentioned. I get average 38 mpg 50-50 motorway and local running.
Also it depends on your style of driving. Drive like a nun, allow the speed to build up slowly, slow down when you see red light on approach, don't go over 60mph on the motorway and you will probably do a lot better.
My wife says that I never listen or something like that !
2.2 diesel Diamond 63. Swift Challenger 580