I live in toronto, ontario, and have noticed my fuel ecnomoy to be decreasing. Is it possible with seasons changing that I ;m burning more fuel becuase of the cold, and using more heat?? I run 94 octane all the time, I use to get 440- 460 kms per tank, now its down to barely 400. The last part of the tank i drive slow too.. soo its not like I'm revign high all the time. .. any thoughts out there???