Bhai your engine is L13A, still you got 24.
But mera experience kuchh hat ke hai, I also dit it twice in winters without AC. My brother has city 2015, he didn't believe me, kahq that's practically impossible n bla bla...
Phir he once had to travel with me and finally he had to believe. Baaki jis ne maanna hai maanay nahin maanna to na maanay but im ready for any type of challenge.
With me, my wife and 1 kid alongwith two attache cases it did 360 kms in 10.17 litres giving me an average of 35.3 kmpl.
Next time (this March) I tried with me, my brother, mother, wife and two kids with trunk full of of 4 attaches and certain other luggage I achieved 350 kms in 11 litres, giving me an average of 31 kmpl.
Believe it or not. Up to you.