What do you mean TRYING to hit 80 mph. Running around here local not towing I average 14.5 to 15 with 16 to 16.5 hwy and I have a heavy foot.

 

well actually i don't just try i do get there with my truck which is the one in my sig. what i was wondering about is would the fact that we are pulling in mostly hills(actually the Cumberland Mountains) affect the fuel mileage that much?

on edit: that 80mph is with the trailer on, without the trailer i never have trouble passing then it is 100+mph. jk

 

You guys are scaring me, ten , 800 mile rt , Detroit to Milwaukee, commute last year. 21.1mpg. I kept it at 71 mph which seemed to be the sweet spot. I run with
Toyo 285 @ 80lbs. 4:10 rear end. 6637 mod. Rotilla , Diesel Klean, Loaned it to my brother-in-law for a trip to S. C. hauling a car down and empty coming back . He claims 22mpg avg. Guess I got a good one.

CC, LB, Auto, 4x4,7.3, 98k miles , new hpop and cps, fuel and oil filters every 4000 miles.

 

I can get to 24 mpg with a little effort, but it is boring and ****'s off the drivers behind me cuz I'm only doing 62-63 mph in the slow lane.

 

I got 17 once. I went 60mph for 5 hour drive home from up north(I had no rush to get home and it was a nice day out so I relaxed). Since then I have never gotten that high. My average lately is 14.

 

Man just be happy with our 7.3's The new 6.4 getting 10 not pulling nothing but that is in town on a good day....thats what my guys at work are getting..

 

My bud at work got himself a new one(08)loaded. put three tanks thru it ( 8mpg)and parked it in the barn........so much for his retirement plans to drag his 5th wheel around the country......Still if I had his money , Id burn mine.

 

Just to chime in again, I drive to work about 4 miles of in-town streets then about 20 on interstate with cruise set at 60 most of the time. Sometimes I'm in a little hurry getting home in the afternoon and get between 65 and 75. I still get about 18 MPG at the pump. I show 17.2 on the overhead lie-o-meter. My 7.3 is bone stock and I believe I have the 3.73:1 rear end.

When I'm towing, I get 9 MPG at 65 MPH. Much faster and things go downhill fast. Since I only have a SRW set up, 65 is plenty fast. I don't see a change in RPM's on the tach, but the mileage goes down. I guess the engine is using more diesel to maintain the same RPMs.

Off topic: don't try to drive a diesel truck into the backyard after a few days of rain. The front wheels will sink deep! Want to know how I know?

 

hey Glenn, that is funny about the muddy yard. i had a cousin who did with her bro-in-law's brand-new 08 dodge dually, she buried that thing up to the doors and it had less than 300 miles

 

My '99 F250 XLT RWD 7.3 manual trans gets on average 17-18 mpg around town and averages a little over 22mpg at freeway speeds on trips over level ground--it drops back to about the 17-18 mpg average in hilly terrain on the interstates but down to 14-15 mpg on crooked hilly state highways. Pulling a 4,000 lb. travel trailer seems to drop those averages about 30 percent. I installed a 4" exhaust from the turbo back, a 6637 filter and run the Diablosport 80 hp tune and a steady diet of DieselKleen. As long as I keep my foot out of it it's pretty economical.
I have a 98 F150XL with an auto trans and the 4.2L V6 that gets about the same average mileage as the diesel(both are 8 footers with caps and extended cabs) but it can't pull that trailer over 65 mph on level ground and in the hills with the trailer it never got out of 2nd gear unless it was going downhill (that's why I got the diesel). So right now I drive the gasser locally (northern Ohio) and save a little money on fuel. If I have to drag something heavy I use the 250.
The big fuelsaver on both of 'em is driving with a light foot. I don't poke along but I take it easy on acceleration and try to time the lights/traffic to avoid having to start over and build up speed again.

 

My '02 DRW F-350 normally gets 14/15 to 16 on the highway. The amazing thing is that pulling a 15K fiver it gets between 10 and 12 mpg. Compare that to my '91 460 gasser which gets about 5.5 pulling the same trailer.