I just took my mothers 2003 Expy on 500 mile trip (3:73 gears and 5.4, 20,000 miles, stock) and besides from getting around 17 MPG running 80-85 the whole way, it ran a hell of alot better than my f150 (2000, 3:55 gears, 5.4, 160,000 miles ) does. Both are 4x4 but I have a few mods (FIPK, Magnaflow muffler & converters, Troyer 87 tow tune). It has made me question if there are any differences in the engines. When I go to Dallas (approx 350 miles away) I am lucky to get 16 MPG running 65-70mph.

 

no difference, you have higher gears and 140,000 more miles.

 

From what I understand (my mom has owned 5 Expy's) the engines are tuned a little more different. This is ust from my understanding other than that I have no idea. My mom's she had tuned like the F150 (because she hauls a horse trailer). Now her truck gets less gas-milage but better at towing. This is what I gather, not 100% on that.
~Phil

 

well they could be tuned for less power, and more mpg...

 

Its what I understand. After she took it to the Ford dealership and told her that my 4.6 towed more than her 5.4 they re-tuned it and it dropped 2-3 MPG but gained a lot more torque. I think that Ford believed (and this is true for most of thier EXPY market) that most people buy them as a Family SUV and not a Work SUV. Well thats just my $.02.
~Phil

 

My mother's 4.6 Expedition has a COMPLETELY different transmission shift strategy than my 5.4. If I had her tranny/gears, I'd probably get a lot better gas mileage too. It does weird stuff, like unlock the tq converter in O/D etc. But mine does have the E4OD....

 

My '05 SCrew and '06 EB Expedition both have the 5.4L and 3.73 rear end. The engine is exactly the same. The Expedition gets about 1 MPG more than the SCrew. The Expedition tranny definitely seems to shift differently than the SCrew.

I just did a cross country run in my FX4 SCrew and got 17.88 MPG at an average speed of 76 MPH (according to my GPS). No mods, the truck is stock.

 

Aren't the Expys somewhat more aerodynamic?

 

My 2003 Expy did the same thing. Start up a slight grade and before it would downshift out of overdrive, it would unlock the Torq converter and bump up about 300-400 rpm. Sometimes it was just enough to keep it in overdrive.

You would think so, unless the F150 has a shell. Then it might be the same.

 

I know! I REALLY wish my E4OD would do that! It would NEVER exit 4th gear then... But there's probably a reason that it doesn't...

 

I own both a 99 F-150 and 00 EB Expy both with the 5.4 and I get better mileage in the truck by a 1-2 mpg.
Both have the 3:55 rearend but the F-150 tends to downshift quicker on the hills while the Expy stays in OD longer on the highway. Either than that they are exactly the same motor. I would imagine the Expy is heavier and any sort of wind effects it on the highway. ( a big brick on 4 wheels )