I really never noticed that much difference with my MPG in my '13 F150 XLT 5.0 between winter and summer driving. My new '19 3.5 EB with 7K miles has been averaging 17 -17.7 city driving since I got it in June.
The last tank was horrible....LOM showing 13.6 and I'm thinking something is wrong with the computer or something. Sure enough...I filled up and check with a calc......13.5 MPG.
I'm 61 and my wife tells me that I drive like an old man.....which I do because I am . No spirited driving at all, I take it quite easy actually.
Just wondering if this is normal in winter for the 3.5 EB....as I thought it would do way better than this. I know that the normal is, winter blend drops somewhat in MPG...but I didn't think it would be THAT much...!

 

I have a 2.7L and have noticed a big difference. I usually average almost 23mpg but am only getting around 18-19. I do a lot of highway driving, but I think the difference is exasperated by having turbos and the aerodynamics of a brick.

 

Mine has dropped by some but not too bad. I have a 3.5 2015 screw and get 18.5 overall. Just took a trip only around 200 miles but got 20.0 even at 73 mph cruise set. I know it sounds crazy but I saw a slight rise in mpg after I installed my catch can. In the winter I seem to get more condensation in my system. I believe that catching it keeps my octane and fuel quality better. Not letting that moisture & oil mix dilute my gas. Just what I see in my truck....

 

Normal, it's winter and everything is stiff from the cold and your tires are a couple pounds down too.

 

So far getting 15 city and 19.5-20.5 highway, I just got the truck last month so no history for normal gas mpg. Hopefully I will see a increase in summer.

2.7l 4x4

 

I almost started a thread on this a month or two back. I've always noticed a drop when the winter gas hits but this year seems to be even worse. I've gone from 18 mpg on average to 16 with no changes in my driving. I agree the cold helps add to the loss but it sure is more noticeable this year.

One of the biggest killers is idling. If you're letting the truck warm up much that could easily be the difference along with the winter gas, lower tire pressure etc.

 

X2 idling is the killer especially when it's cold out and it takes the idle 5 minutes sometimes to drop under a 1,000 rpm!!

 

Winter blend fuel, extended idling to warm up the truck, colder more oxygen dense air, oil thickening in the cold, use of 4x4 (if applicable) are just a few of the added variables that factor into MPG in the winter. Every vehicle I have ever owned has suffered in the winter in the MPG department for various reasons. My current 2015 3.5 Lariat dropped a solid 2 MPG average since winter hit, I was fully expecting that though.

 

I think the only issue is OP not noticing the difference in years past.

 

My 2.7 drops 2-3 MPG in the winter. 4 seems excessive and 13.5 is pretty bad. Especially in Arkansas, where I presume it has not been all that cold.