GTI CAB POOR MPG !HELP!

hello all!
this is the second cab i've owned, the first being a 1.8 carb and i never had the same problem with that one!
in my gti, i'm getting (on average) 9mpg around town and 16mpg on a good run.
its not as pokey as i expected, and i cant go on spending money on fuel every five minutes.
ive had the car serviced and the timing belt set up correctly. since then its become slightly more responsive but i'm still getting a shocking mpg reading.
anything obvious i should be looking at or is this just a case of it being an old car? haha
any suggestions would be appreciated!

is this actual calculated mpg or just what its showing you on the mfa?