Blimey, what are you people doing, are you actually moving
I'm lucky to get about 43mpg out of my V50 2.0d and it is usually nearer to 41. I try not to exceed 80 on the motorway (usually can't anyway for the traffic) and the a road stuff is only fast at the weekends.
My computer indicates about 46.5mpg which I wouldn't mind if it was real.
I just put it down to the fact that it's quite a heavy car for it's size....