218d 150ps engine is too small for the size of the car to get decent mpg, the 2 GT is similar weight to our old 520d 190ps and the best that would do was low 40's and 30mpg around town.
My 220d is 46mpg average, around town it's noticeably poor but good at 70-80mph.
my 220d Xdrive is showing an average of 45.1 mpg over the last 6,511 miles
that's probably a 50/50 mix of town driving and long distance motorway