Not trying to start a bashing thread, all around was very happy with the mileage. But I noticed as the temperature dropped to -20C or lower I seemed to lose 5L/100km. My mileage on the highway at 105km/hr went from 13L/100km (18mpg us) to 18L/100km (13mpg us). Anyone else experience this? I don't know how much my mileage dropped on my old 5.4L as it didn't calculate the mileage and it very well could have been this much.

Just want to know if this is normal.

 

If your trips are short, mileage will be poor because it's not getting to operating temp.

 

It was about an hour into my trip that I checked. I had looked at it this fall when it was about 15C and then again the other day when it was -23C.

That being said, I do not have a front cover on my truck so the fluids could be cold. Never checked my tranny temp.

EDIT: There are lots of different variables that I didn't take into consideration, ie, winter gas. But the I was running 93 octane this time and only 87 last time I checked. Tire pressure was the same as I bumped up the pressure after it got cold.

 

All of my vehicles lose an average of 2 mpg in the winter. A big part of it is the crap winter blend they call gasoline. Throw in some remote starts and in my case, big gnarly mud tires, and might as well forget it. My 5.0 also feels a performance drop on the winter blend fuel. I actually notice a difference in winter running 93 octane vs. 87. Not scientific, but on the same drive, truck downshifts 1 gear on one interstate hill on winter 87 but not winter 93. In the warmer months it doesn't downshift on either grade.

 

I went from 13l/100km to 14.8 per 100km