I have 1.6 2015, 7000+ kms driven. Maximum I get is 11.7 in slow moving highly congested, stop and brake traffic on Islamabad Expressway daily run 50 kms at least.
Confirmed by full tank method, the reading of fuel average calculator is very close.
If you fill up and reset the average meter, it shows 15, 13 and 12 for sometime, but in a couple of days the real average comes which is in 11s.
Whenever, I have a smooth run the average gets better, but in slow traffic it drops.