Average an indicated 20-22 MPG per tank depending on what my driving is like that week. The bulk of my driving nowadays is highway commuting and a large portion of it is at low traffic hours so I can cruise and get good mileage.
Now, what the ACTUAL mpg is I don't know since I haven't gone as far as to fill the tank, run it down, record the mileage and see how much it takes to fill up etc etc, but I'm averaging in the 600-630km per tank range when doing a lot of highway and I'm GUESSING that lands me in the 20ish MPG range. Too lazy to do the conversion right now. I live in Canada, go by km for speed and distance, but measure fuel econ in MPG. Go figure.
Either way, I'm getting slightly better fuel econ than my last car, which was 1000lbs lighter, 100+ horsepower fewer, and was MORE aerodynamic than this rather brick-like ST, and yet I picked up better econ. Not complaining lol