I know I don't have any 41's like the dude above, but with my new Trail Grapps I got a little over 13mpg on the HWY (about avg for me). I don't think I've seen 15mpg since I bought the truck over 3 years ago.

 

You guys all have vaild reasons why you get the bad MPG I don't have big tires or any of that mumbojumbo. I mean even though it's blown there's no reason for the SC to cause such a drastic decrease in fuel mileage.

 

Like I said earlier, I believe its due to the winter blend fuel.

 

I hear what you are saying but 9mpg on a stock f150 is not right even on winter fuel.

OP I would say check a leaky injector or dragging brakes

 

Just thinking here. Could be your tune. I assume it's still stock. Ford may have written the tunes to run rich in colder weather to prevent detonation with the blower. Might want to look into a custom tune if none of the other things posters have suggested help.

 

Well he's also supercharged and that requires quite a bit more fuel than a normal stock F150. And winter blend fuel may have even more of a negative effect given that fact. Im not sure, just throwin' it out there as a possibility.

 

is this your first winter with the truck? i have a lead foot since a month ago cuz of the new muffler but even then im at 12.5 doing the math. 12.9 on the dash...but im in florida i dont think they believe in that winter blend stuff

 

Bump tire pressure up 2 psi cold, change fuel filter and clean your TB. I run Shell in AR, Chevron in LA & MS and Conoco in MO & TX. I have always received my best highway mileage (20+ mpg) on Conoco 87 octane.

I just received 21.1 mpg on Conoco 87 octane driving the posted speed limit from just south of Sikeston, MO to Cabot, AR. I had my tuner on 87 Tune with tires at 36 psi/38 psi cold with a full bed of firewood and the soft tonneau cover on.

 

You also have a 4.6 as opposed to the 5.4. Best I got with my 5.4 was 18 all highway. its now around 15-16 with my mud terrains.

 

Sorry I missed that he was supercharged. All I saw was stock in one of his posts.

My bad, it could def be the cold weather and winter blend fuel.

 

I understand he has a 5.4L SC Harley Edition. Gas brands have always made a big difference in all my Ford's.

I average 18.9 mpg on Shell (E10), 19.1 mpg on Chevron (E10) and 20+ mpg on Conoco (E10) and Conoco 100% gas. My combined city/highway mileage on Shell (E10) gas is 16.9 mpg. I always attempt to set cruise control on the posted speed limit.

I usually set my tires 2 psi higher than oem spec on road trips.

 

No biggie, its sometimes easy to miss as some people just say "SC" instead of super charged.

 

could be a crappy set of O2 sensors or how you drive the truck, I can run my truck hard and still get 13mpg even in the winter I'll get 17-18.