My d24 940 gets between 34 and 38mpg, this translates to between 420 and 480 miles per tank. this is 150 miles every day, 135miles motorway at 75mph or so and 15 miles of city and B roads....
And i usually floor it away from most roundabouts... especially in the wet. know, because hard spots on tires are dangerous....
I have managed 47mpg when i followed trucks to and from work for a tank... that was boring!