Bought XM Diesel variant in October and this is my review post first service.
The car is a beast to drive, I have clocked 2200 kms and getting a staggering average of 26 kmpl in City Mode (without AC, in Delhi traffic). I still haven't explored Sport mode which I have been told is extremely powerful. You can feel power lag in Eco mode which I do not prefer to drive.
All in all you might not get the punchiness like a Honda or Hyundai but in city conditions drive is really smooth. Built quality inside is good and gives the car an upmarket feel.
I would not suggest Petrol Nexon as I have heard average of around 8-10 kmpl in Automatic and 12-13 kmpl in Manual.