City is surviving in the market because of it being associated with the diggi wali family car image.
Other then that people already prefer Vitz and Aqua over City and even Gli.
Where as fuel average in concerned im getting 12 with and 14 without AC on a WagonR so 15-16 km/L are just claims i dont know how to people get. Even my 2010 Corolla Gli manages 14 km/L with a light foot with out AC.
So the summary is City is a tin can but its looks decent becasue a of diggi.
You feel more good stepping out of a 1.7 Million diggi wali gari rather the a 2 million hatch back.
and the 17-24 km/L average that comes with Aqua comes with a cost of other maintenance as well. its not just fuel and go. Either you change the car every year or prepare for other expenses along the ride