Just completed an 866.9 mile trip without the trailer with my 06 5.4L EC 4x4 XLT with 3.55 gears and 255/70x17 tires. The truck just turned 50,000 on this trip. For the entire trip I used 48.1 gallons of 89 octane and averaged 18.0 mpg driving the 70-75 mph for the most part. There is about 50 miles of city or county road driving and a couple of hundred miles at 60-65 mph in the mix. Considering the conditions and the speeds I was driving, I'm very pleasantly surprised with the fuel mileage. I was expecting high 16's or low 17's for fuel mileage. And for the record I used BP, Shell, and Marathon gas. The first 200 miles I got 19.6 mpg driving 60-65 mph. The next 320 miles I averaged 17.4 mpg driving 70-75 mph with approximately 80 miles of county road or state highway driving. The last 340 miles I averaged 17.8 on the Interstate except for 40 miles of state highway driving 70-75 mph. Just thought I'd throw this out there since it's been awhile since any fuel mileage threads have posted up on this generation of F150.

 

I have made several round trip trips to the mountains and I have gotten mid 17's on all the trips. OK by me.

 

I'm going on a 3000+ miles road trip next month. I'm anxious to see how it turns out. Will be going north to Pacific Northwest then back home in NM. I'm expecting to get 15-17 mpg average. Will be logging in the actual calculated mileage for the entire trip. Will share with you guys. Gonna rotate my Michelin tires beforehand.
Went on a Montana Christmas trip earlier, got 16 mpg average, 15.5 mpg all the way up then 16.5 mpg back home. Drove 5 mph slower back home.

 

Speed definately affects mileage. Quality of fuel does as well. On previous trips under similar conditions using the cheapest or most convenient gas I was getting high 16's to low 17's for fuel mileage. This trip the speed was like previous trips as was weather conditions. But the fuel was better quality and had less ethonol content.

 

Did you go yet ?

How'd your truck do ?

 

Been calculating mileage since purchasing my 2004 one year ago. 5.4, 3.73 gears, 18 " wheels.
Average 14.1 all driving.
Max 16.8 Mt run down interstate 70 mph.
Low 12.75 winter city.
this weekend towing pop up camper about 2500 lbs. interstate. 14.4 mpg. Air conditioning, 65 to 70 mph. 400 mile trip . 95 degrees average temp.
Calculated at time of fill actual miles and gallons used. Electronic monitor usually about a half a mile per gallon high.

 

I just posted my result in new thread. Check it out. The one with 5000 miles road trip.

 

I find that the on board MPG computer calculation is not that far off. I track my mileage with the Gas Cubby app on my Iphone. Over 16 tanks I am getting 13.7 mpg as calculated by the app. Over those same 16 tanks my on board is reading 14.2 mpg. That is only a.5 mpg difference. I did not re set the on board even once over those 16 tanks so that I would get an apples to apples comparison.