coz 80 to 90 speed is more for this. if you drive between 70-80 you will get good.
I got average in less, but on outside at speed 120 got good average, but again if I drive at 150-160 average came down. so same with your vehicle. 80-90 is very less speed but for this vehicle is not less. I remember once I come from faislabad to lahore on bolan, I full press the race per not cross 95.