I have travelled 3 times on motorway with this car, each time with different average speeds. In first 1000km break-in period, i drove at 100kmph speed and it gave me 17.8Km/L average. The next time I travelled with 110 and it was around 16. Last time I pushed the engine and drove at 125 and it was around 15... so on highways you should not be worried about the fuel consumption.
Locally I am getting 10-12Km/L and I don't think that's a bad average for 1.5 engine in urban and extra-urban conditions. Infact I have stopped looking at the meter anymore.
Having owned a 1.3 City 2013 model previously, I didn't expect much from this car, but 1.5 prosmatic is surprisingly good in terms of fuel and comfort.