It gives way better fuel average if driven at speed (80-100) and there is no rush on the road, means your journey, even if it is in city, is smooth.
When I have to drive slow and stop and go style in rush of Islamabad Highway and PWD, the average drops to 11.5 kms/lit. But in late hours when there is less traffic, Altis 1.6 give amazing average.
If you idle, the average drops suddenly.
And yes, reset the average after every tank full