In San Jose I'd say never, we should already be starting to get it here.

 

Does my 2008 F350 4x4 CC SRW 8' bed have a 38gal tank ??

 

Yes, it's a 38 gal. tank.

 

The best most honest MPG I've ever attained on my 08 SRW 4X4 Super crew 3.73 rear end, was about 20 MPG. I was traveling 125 miles, at night, no wind, freeway. Elevations from 4000 to 6000 feet, rolling terrain. I think I had kept my RPMs to about 1900. Like Senix, I play at keeping the boost as low as practical. I had about 20K miles on it at the time.

I am getting about 16 to 17 typically. I try not to jackrabbit start and ease into speed when I can. If I am approaching stop lights, I do the best I can (without pissing off my fellow livestock) to hit them green or at least let others trip them to green for me. Getting trucks as big as these rolling from a dead stop sucks fuel like crazy.

Towing is completely different though. I haven't really found that "zone" for pulling my RV and getting anything to brag about. I am in there about 9 MPG average going about 65 MPH. Probably typical.

 

a few months ago I would easily hand calculate 16mpg on my 2010 F-250 CC/SB 4x4 with 3.55 gears (even as high as 18mpg driving nice). Two weeks ago I drove 196 miles on flat terrain with only a few stop signs along the way. I folded in the mirrors, never used cruise, kept it under 60mph and kept the boost below 10psi when possible. I filled up when I got to my destination and only got 13.7mpg hand calculated. I left my house at 4am and there was no wind. On the way home I drove like I normally would and got 12.4 hand calculated. I don't understand why I would lose 25% of my fuel economy. The fuel filter was changed shortly after I noticed the drop in MPG thinking that was the problem. I also started using Ford's Cetane Boost which has not helped the MPG. I have started writing down my regen mileage and it has varied between 85-220 miles between regens mostly driving empty. Seems to be something wrong with the truck, but the dealer says "no codes, no problems". Anyone experience a drop in mileage like this???

 

when I did there was a hidden code in the history. Had to do with an overboost situation.

 

how many miles do you have? when was the last time you changed your air filer?

 

I was hoping that code was going to be there.....but there was nothing. I did see the gauge pegged at 40, and was able to get a picture of it at 38, but the dealer didn't seem to think much about it

The truck has 62,000 miles and about 10K on the air filter

 

My symtoms were not so much how much boost I could produce under load but rather when I was empty on country roads where I would normally see no boost or just a needles worth. In those cases I was producing 10-15psi.

 

Keep in mind that certain area's of the country have already seen sub freezing temps and winterized fuel is being pumped now. The winterize fuel will effect your mileage.

 

Filled up today.
Drove 106.8 miles as easy as I could at 1900 rpm on interstate.
Refilled with 6.6 gals of fuel which equalled only 16.1 mpg on my 2008 F350 4x4 CC SRW 8ft bed.
So I'm kinda bummed.
My 1996 F350 7.3L manual trans will get 19.5 mpg so I'm kinda bummed !!!

 

You don't say what Rear Axle you have but probably 4.10 in that truck and 16 is certainly respectable. It's a big truck and 16 is right around where everyone else is. I drive like that most of the time and I'd take 16 in a heart beat. I don't drive enough empty interstate to bother checking it but I'm pretty sure mine would have come in around 14- 15. Now that I'm tuned it seems better but like I said I've not done a check unloaded.

 

Your comparing apples and hamburgers, your 7.3 does not have a DPF system and the power output between the 2 is totally different.

 

3.73 Axle in my 2008 6.4L
4.10 Axle in my 1996 7.3L

I have removed the DPFE & CAT on the 6.4L & only get 16.1 MPG

 

who's tunes are you running and what tune?