Not surprising, although fuel consumption (unless totally out of whack which would indicate an engine problem) is no concern of mine, and I never bothered checking.
Might give you an indication : with my SDrive 20d I clock approx 900 kms on a single full tank. You do the math.
I even reached close to 1100 kms last Fall, when aircon is not needed and with my driving style (call it conscious eco-driving!
)
Driving style is always the key though.. I could probably bring it down to 12 miles a gallon if I drove it like my company car for which I don't pay for gas..