Offtrac I won't agree with that entirely...
the average MPG/Performance is a slippery slope of missed opportunities and misguided expectations.
You are correct: the Explorer/Monty platform prior to the current "uni-body" platform is basically an archaic station-wagon, on a truck frame, set high in the air, and bred with the aerodynamics of a brick... We all get that. However... when my wife's '04 Monty (4.6L V8, AWD, family of 4, with christmas travel trimmings) can tow a heavy Uhaul trailer through the hills of Missouri, pulling a 3,000# Mustang and associated parts and average 15mpg with under $400 in logical mods, WITHOUT a ECM tuner... I think that's a pretty big performance/MPG WIN!
Her truck (before the recent bearing failure) averaged 17-19mpg (combined driving) with only attention to intake flow, maintaining the basics, good fuel, and proper tire type and inflation. And I am NOT **** about her truck's up-keep as I should be. It goes over on oil change interval, it needs a fuel filter, and don't get me started on the trans-fluid cycle... I'm lucky on that one... shame on me...
"Performance" and "economy" are very personal definitions and perspectives AND also
dependent on the OE's original design.
EXample: My '04 Subaru WRX gets 23.223 MPG no matter how hard I drive it or how easy I take it.. nothing I have applied to the Monty has worked on the WRX.
the Monty, as stated int he link provided, has the so called "stage 2" intake tract upgrade, stage 1 air box mods, upgraded coil packs, Fuzion brand tire which were chosen for specs that maximized the roll diam and minimized roll resistance. Copper NGK plugs changed every 15-17,000 miles, etc etc... the Monty has 183K on it and right up until the bearings started clatttering like Reindeer hoves on a tin roof, it GAINED 2 mpg average to 21mpg combined.
All I am trying to point out is looking at a stock Explorer/Monty, as I see it, and have said before: The majority of units sold were with the 4.0L V-6. Fine... Many argued tha the "paltry" 15-25hp difference between the V-6 vs the V-8 didn't warrant the expense or the expected lower MPG of the V-8... Physics is a funny thing... In order for that V-6 to make up the lower HP it has to still over come the same gross weight. therefore ALWAYS the 4.0L will be working harder. To leave the stop light, tow those jet ski's, dig through that snow, whatever you throw at it, the 4.0L is working harder... even at steady cruise, the v-6 is working harder. I've heard guys/gals say the best MPG out of the 4.0L is 12-14mpg...

I'd freak out if there wasn't a parking brake hung up or something...
Its all about perspective and expectations... You can't haul the family of 4, all the Christmas gifts for the extended family, and suitcases in a Yaris or even my WRX Wagon... simply won't work.
Nor will a typical Explorer/Monty run 12, 14, even 15 sec in the 1/4 mile...
Rob