I have a 2016 GLi AT and it is giving me perfect mileage. In City, be it Lahore or Islamabad it gives me 12-14kmpl and on GT road or motorway it gives me 14-15kmpl. Lowest it has ever given me is 10kmpl. I used hi octance before, but I have stopped using as it doesn't increase the performance not does it have any advantage to the fuel economy. With adding Hi Octance I feel car runs a little rough.
And I calculate my mileage manually everytime I refuel.