Im now approaching 4000 kms on my 18iDrive and consumption wavers around 12.5lt, averaging about 28km/hr. Its not that far off BMW's figures of 11lt for urban driving. With more conservative driving, and slightly higher average speeds, its probably achievable.
Manicm, i tried manual shifting, and it definitely improves fuel consumption.
I have also found the auto transmission to be more settled now than originally. Gear changes are smoother and dont hold on for so long in 1st to 2nd. It probably makes sense for the auto to hold gears a bit longer given the poor power-weight ratio.