Have just been reading this thread as I owned one about 4 years ago I once got 27 mpg on a full tank mixed driving that was the best it ever did in my ownership was doing 16 mpg urban in the bad winter of 2010/11.
I've had my St3 around 6 months. Managed around 35mpg on a long run down south once. Typically manage around 22mpg I do live in North Wales and have a fantastic route to drive to work in the early hours though... 17 mpg is pretty easy to average if giving it some.
