I have a 2008 F-150 Supercrew with the 5.4L in it. I get around 15 to 16 AMPG without a trailer on it. (highway miles). I towed our 30ft. Outback that weights 6660 pounds dry. And I was getting around 13.5 to 14.0 AMPG. The way I was reading this was on my edge evo. Is that thing right? I was thinking I would be around 10 or something lower.

What I have on the truck is

K&N Air Changer System
PowerAID Spacer
Edge Evo on level 2 with 89oct.

Is 13.5 to 14.0 right?

 

The only way to accurately determine gas mileage is do math. Fill the tank, zero the trip odometer, drive it, then fill it again. Divide the miles driven by how many gallons it took to fill it. You also need to make sure your odometer is accurate, which it will NOT be if you change the tire size or gears.

 

As glc said, best way is by math. I've never checked my mileage by math while towing but I will say mine drops to 13 to 14 on the Edge at 75mph pulling a 6x10 enclosed loaded with tools, two motorcyles and all the gear. Mine is an 06 FX4 with 3.73 gears. I average around 16mpg otherwise.

Next trip I need to fill up right before we leave and then do the math when we stop for fuel, I guess. It just never really concerned me that much.

 

Yep the best way is the math way but the Edge does give a faily accurate estimation. My truck gets 15-16 with out my 6000 lb camp trailer and about 11-12 with it. I have a 2v 99..

 

Mine drops down to 9-10 mpg (from 15-16 without) pulling a 8,000 lb TT. That's going by my message center. 05 Lariat 4x4 scab, 5.4, 3.73's

 

Well geez my '99 4.6L 3.73 gets right at 20 MPG unloaded on the highway at 1800 rpm. On long trips where I cruise for a full tank between stops my hand calculated mileage is 21.8 MPG. The secret is keeping my foot out of it and cruising at a comfortable 65 mph.

My Evo instantaneous MPG says 23.x on the highway at 1800 rpm. Wishful thinking.

The odometer is correct. I use the Evo to correct for a slightly larger than stock tire size and the "squish" factor. Verified using real time kinematic corrected GPS.

The specs: Evo on Level II, Magnaflow exhaust, all else is stock.

 

I get about 14.5 unloaded with 2008 Screw with 3.73 and about 11 carrying my 8 foot Palomino slide in camper at about 1500 lbs plus gear and pulling a 14 ft aluminum fishing boat.