I have no idea how you (and tons of other people) are getting those numbers. I also drive a SCrew, 3.31 elocker, 36 gal, fx4 and OE 20s". City I get 17, HWY I get 19.x. I have 17K miles on it right now, so I dont know if it gets better with more mileage.

 

toss the high gears for low ones and you'll get some more mileage out of her. I get 18-19 combined with 4:09s and 35 inch tires

 

Just drive em all, whatever one you like jus make sure you google your axle code off the door so you know what gears it has in it. That was my problem but I knew I'd get new a ring n pinion for the set up I wanted to accomplish.

If you feel like you need a Ego boost, then get an Eco boost if your feelin like an angry wild wanderer get the coyote with low gears 😂

 

If you don't tow heavy daily/weekly, the 2.7 is perfect. I'll get anywhere from 24-29 MPG on the highway (60/65 mph limits here). I've towed a 7500 lb boat (boat+trailer) no problem, and my 20ft travel trailer is 4500 lbs tandem axle with a flat front and I get between 9.5-13 MPG depending on headwind. Tows easily, but not as aerodynamic as a boat. I'm sure other engines might get better tow mileage, but since I'm not towing 99% of the time, the 2.7 is perfect for my needs.

 

right foot and speed determine MPG, not the gearing, it's irrelevant. The slower the engine turns, the more efficient it is supposed to be. 3.15 are good highway gears, but you reach a point where the best combination of gears can't overcome the drag induced by speed. 3.73 are good for towing, but are not that great for highway since it puts the RPM's up high.

Throw that all out the window when you put oversize tires on though, then gear to get the best low RPM at speed you can.

 

Agreed with acdii for the most part, but gearing can help a little. I have the 3.73's which makes for good easy acceleration, especially when towing. Highways speeds are still pretty good if you live in Canada since our speed limits are 60 MPH (100 km/h), with some major highways being 65 (110) in Alberta. But anything over that makes your mileage take a dump. Also, smooth driving helps. Don't pull up to a red light going fast and slam the brakes. I coast, and sometimes the light turns green before I get there so I just have to pickup a bit of speed instead of starting from a stop. And in bumper-to-bumper traffic, I keep my distance and keep rolling at a lower speeds instead of playing the accordion game where everyone hits the gas hard, slams the brake, and repeat...


I think the 2.7 and 3.73's are a good match because it makes stop-and-go driving more efficient (Imagine pedalling a bicycle from a stop on easier gear vs harder gear).

 

2.7 all the way.

 

Thanks for the replies. I do drive somewhat slow, but dont do jackrabbit starts. I drive conservatively for a truck.

I wonder if dumping the 3.31s for 3.73s would help. The cost is pretty steep though.

 

I have 3.31's and love the truck. not sure if the 3.73's would be too much gear but others seem to love em.

 

I have the 3.55s and a 2.7eco. I can run 70 on the highway before mpg takes a dump and still have good acceleration with a load. I had 3.73s in my 5.3l silverado it couldn't mainatain speed on hills pulling a 16ft aluminum boat without flooring it.
So glad I'm back in a Ford!