Wind direction will play a huge factor... and you're still driving waaay too fast to achieve Transport Canada numbers (or are those Ford numbers)! Keep it under 90km/h and you may break 10L/100kms.
Having a Fuelly account will help you keep better track of your numbers. You can even have it in your sig if you choose.
My numbers are all over the board... mind you, I drive like your typical Albertan...
http://www.fuelly.com/driver/stardec...silverado-1500