Sometimes driving too slow does not give you best average. In auto if you are driving too slow that means your car is using lower gear and changing to neutral while approaching traffic signal is not a good practice but yes you can change gear to neutral while waiting for green signal.
I would suggest you to keep your car at fair speed without noticing the RPM because you have auto, you can control the car at certain RPM unless you start changing gears by yourself.
For me you should at least get 11-12 mileage without AC but dont expect it to go beyond 12.5
Take a drive on islamabad highway after resetting the avg and keep your car between 60 to 80
