Honestly, the milleage reflected on the display is rarely accurate, I have checked it a few times as own a similar vehicle, and there is a variation of around 10-15% even though I fill up petrol from the same gas station. Often JDM owners claim that the fuel average displayed, corresponds to the actual fuel consumption,hard for me to chew on. Cutting it short, my 9th gen does 8-9 within city (stop-go driving), and 12-13 on the motorway.