I could understand if i were speeding or pulling but i am not. The truck and tires are stock and I am satalite tracked and do not speed. Often i am oly running @ 80km/hr due to the back roads. Like i say it just seems to change with the weather. It has been into grifiths ford many times(for mantainance and fule millage), and they told me that there has not been enough complaints about the fuel millage, so ford sees no problem. I will attempt to run it to Edsons jerry ford during break up to see if they will help me out with this.