When I go back to KL from SG, travelling at 110-120km/h, I can consistently get >18km/l with my 520i. If I put it into the sport's mode, then it would drop to 16.xkm/l.
But when I drive around town, yaks... Driving in city traffics, 8-9km/l depending on how I drive.
(All done with Caltex 98)