This is a brand new car, 7 miles on the clock, one junction up the motorway, other wise all done on single carriageway/limited dual carriageway motoring. It also included my 'hard break in' acceleration bursts, and a 'few' full afterburner overtakes. Fuel tank level seems to suggest OBD is reasonably accurate...but as always, to be confirmed with fill up logs.
My C220CDi Blue efficiency (no economy slouch) would have clocked just under 50mpg for this route. I'm stoked