I realised Latio can get >17km/l but have to drive at certain pattern. If it is safe to drive a little faster, I will buy some time with that little amount of petrol. I got 16km/l+ before driving at 90~ 100km/h on highway once, and that's it.
FC is depend on 1) how keen you want to set record FC
2) how much you value the time taken over the petrol used.
I get single digit FC in SG but its ok, I am happy with what I have. My one tank last one month, what else can I ask for

My FC will cross 10km/l if I have more green lights on the road.