In addition to the tips already provided .....

• eliminate ANY unnecessary weight that you may have in the bed / cab.
• religiously perform all scheduled maintenance.
• inspect, and if necessary replace, your suspension and steering components.
• lub' all suspension and driveline components.
• check, and if necessary adjust, your wheel alignment.
• USE O/D. *Unless you're towing.
• keep your vehicle clean and polished.

Things noted above that will have little > no effect ...

• after-market CAI | K&N-like air filters. *The stock OEM air intake system is MORE than adequite -UNLESS- you've done EXTENSIVIE performance modifications.
• tonneau cover. *GREAT for keeping the bed dry / clean and keeping things out-of-sight.
  
  The ROI doesn't justify their purchase. Use the $$$$$ saved by not buying the above towards fuel.

Lowering MPG BIGGIES ...

• tire inflation.
• driving habits.

And I'm unanimous on that. .
.

 

I have a 2005 xlt with 5.4 triton. I drive a mix of miles in town and highway. If I set cruise on highway around 72 I get about15.4 mpg. If I set cruise at 65 - 68 I get 17.2 mpg. I think its pretty good mpg for this vehicle, keep foot off the floor is a big help........ I am looking forward to doing the gotts mod though and see what happens

 

Then you gotta come back up the hill!

 

Lots of people are talking about eliminating unnecessary weight.... but what if she's your wife?!?!? Hahaha jk

 

I set the cruise at 70 and see mainly just highway. I'm lucky if my 4.2 can get 16 mpg. The truck only weights 4200 lbs, less than a 04-08 4.2 from the factory.

 

I did the gotts and silencer mods. Haven't seen an mpg increase. I cruise at 68 on highway and light foot in town. with 70 miles round trip to work five days a week I'll see about 15 mpg combined.

 

I just drove Houston to San Marcos area running 75. Got about 16, maybe slightly over. Before I did the Gotts it would've been 14. The Gotts helped me out, but it could also be the fact that I'm not constantly battling West Texas winds when I'm home for the summer.

 

Have only 1250 miles on my 2011 F-150 XLT 4x4 SCrew but I am averaging 16.6 city miles. Haven't made any highway road trips yet but anticipate 19mpg. Be very alert to braking and accelerating(light foot). But of course, you are driving a truck designed to haul loads, me that is a 16.5 foot boat and 26 foot travel trailer. I can trade off gas expense for peace of mind making a weekend or week long road trip with the family.

 

My father and I regularly pull 8K-12K lbs with his 5.9 MegaCab and it pulls just fine. Set the cruise on it at 72 when not pulling and it will average (this was over a 860 mile run from 700 ft asl to 9000 ft asl) 29.3 mpg. That's a completely different beast in it's own right but you should make closer to 20 on the highway with your screw. My 4.2 used to make 19 before the engine started wearing out.

Point is, always use the cruise for best mileage even if it's just for 10 miles. I used to use mine when going to school in the morning (15 miles) and that was back when I would pull 19 mpg due to the slightly lower speeds of Texas Ranch Road driving.

 

Three basic things to do to help fuel mileage.

1. Keep the truck stock (no over-size tires).
2. keep the tire pressure on the high side of specs.
3. Keep your truck maintained and serviced regularly.