The F series gets better mileage because it has far less air resistance.

You can get close to 17 -18mpg on highway, but at 55mph or so...in the van.

Think you need to move to a Ford Transit Connect if mileage is a real issue.

Big vans with huge air resistance can't change the laws of physics.

 

I know the Transits are supposed to be the work truck of choice for the new generation but I'm too old school to go with it. I like my full size trucks with the big tires and imposing looks as much as I like my guns and I don't see either of 'em going down the road anytime in the near future. Like I said in my last post there's additional mileage to be had in any vehicle but it's finding the right combination of modifications to make it happen. Thank's to all for the replys....Jim

 

Look, taller gears decrease MPG in the city as you are constantly stop/go, getting the heavy vehicle rolling kills it. I have a 99 E-350 ext 5.4 with 3.50 gears and get 10 on a good day in the city 9 usually, 15 Hwy when I'm lucky, I want lower gears to make up for it. The scale at the dump had me at 8000 lbs, empty, only a rear bench, stereo system and my wheelchair lift at the side doors, the middle is pretty much empty. I have an exhaust shop cat back Flowmaster 40 duals, Super Chip Micro-tuner (requires high test), removed air intake silencer, and a K&N filter in the factory closed box. I tried an open air element and it decreased the mileage.
You are required to run synthetic in the rear of these vans, it's in it from the factory!

 

BTW on a 200 mile trip to Knoxville, I could not break 15 MPG when I dropped it to 65 MPH, and learned that is a dangerous speed as you get pinned behind truckers going up hill, hard to pass as the speeding cars run you down trying to pass, and the truckers plow over you on the way down the hill. I know this well, the sweet spot of mine is 72, with the cruise, any slower or faster will cause the transmission to search on every little hill, not sure why it holds at that one speed. Also use the overdrive cutout switch as when engaged while going up a hill, with cruise engaged, you retain 3rd gear, turned on, the transmission down shifts as it should, but often to 2nd, sounds good while doing 70 MPH.

 

Good advice. Thank's.

 

I'm very happy with the MPGs I get with my bone stock (no muffler) 2000 E350 Extended 7.3PSD...3.55 rear. I've hit 21.3mpg on on trip with a strong tail wind. But usually I get 18.5-19 MPG.
Most of the time I have about 600-700 lbs aboard.

Tip for getting better MPGs, skinny tall tires. clean oil, and clean exterior- as in waxed.
Although I have 265/75-16 BFGs AT lol...

 

What year is your 4.9L?

my 4.9L averages 19mpg on the the hwy with a load more than or around 800+ lbs. and 15mpg in the city. it has the 3sp auto and i rarely go above 60mph on the hwy.