About 13.5 in city driving. As it gets colder, that can drop as low as 12. Plan on about 2MPG better with the 35i. Nothing huge.
BTW, highway normally around 22MPG with my 50i.
Our Clubman S gets 29MPG in the city however.
2012 Vermillion X6 50i -CWP, Vent Seats, Tech, Sport, Premium Sound, Premium, Active Steering, 3 rear seats, BMW Apps, Space Saver Spare
2011 1M, Black loaded sans sat radio