I've done 7,000kms in my 320d and my average is showing as 5.7L/100kms. Almost all of my driving is city driving - a few weeks back I got up to 5.8L but then I did a trip from Sydney to Kalkite and back (~900kms) and it dropped down to 5.6L, since then it's back up to my normal 5.7L.
On the trip to Kalkite I managed to get a total of just over 1,100kms for the tank.
2016 F15 X5 XDrive30d M Sport
2012 F30 320d Luxury