It depends.
From experience:
If you cruise on the motorway in no particular hurry you'll see > 36mpg at a GPS indicated 70mph on the computer,
At a GPS indicated 80 I guess (because I wouldn't know

)you'll see closer to 32mpg
If you are gentle and tool around on A roads and B roads you'll see 30-32mpg
In town you're likely to see mid to high 20's - depending on traffic
If you drive it hard on non-motorways low to mid 20's mpg...
Mine is standard.
Given the perrformance available I think it is pretty good on fuel but on large throttle openings will see it drink quite heavily - not a problem for me.
I suspect my average over 32,000 miles (I picked mine up a year ago today) would be around 28-30mpg although I haven't measured it probably 75%-80% of my driving is on motorway/dual carriageway.