my avergae to date is 40.9 over 5000 miles. obviosuly depends upon how you drive it and the conditions you are driving it in.
When I compare mine to my previosu E39 530I, its 50% better .
25mpg in heavy town.
35mpg in light traffic around town
40-45mpg on motorway up to 70mph
upto 58mpg on very easy motorway at 60mph
generally don't thrash it but nice to know the pwoer is there and on occasions I use it which brings a smile to my face!
your figures don't sound unreasonable though.
rember its a nigh on a 1.8 ton car that can get you to 60 in ~6.0 seconds.thats pretty impressive in my book.