I get 10-11 mpg depending on how happy I get with the go-pedal. The worst I've gotten was 8 mpg hauling arse with the toyhauler one trip. Towing my 35' Haulmark race trailer I can get 12-13.

03 f350 7.3 6 speed duelly crew cab 4x4 13 mpg twg or not... running 18 to 21 rpms

My 04 GMC DMAX on 37R17s, 4:55 gears, Pine Valley Auto Exhaust (no PDF of muffler), Volant CAI, Predator programmer and Banks IC towing my '08 40 footer fully loaded i get roughly 10-12ish at 60 MPH. Not towing anything around 20ish.

1994 class A
454
26' enclosed.
Towing HEAVY (26K GCVW) we get 6.7 - 7.2 @ 55

Solo: 9.7 @ 65+

06 f-350 6.0 power stroke diesel with 4:30 gears and 35" tires. 4" lift in front only for the flatbiller stance on truck. i tow an 08 cr-3905 weekend warrior with a ktm 525, raptor 700, raptor 350, honda crf 50, suzuki quadsport z90, 150 gallons of water and food, etc. 7-9 mpg. i tow in the 60mph range. it keeps my rpm's right where i like them, and keeps mileage half way human while i tow. mileage is hand calculated by miles driven and amount of fuel replaced at a fuel stop. on a windy day with wicked head winds, you can drop that number to about 5.5 - 7 mpg.

towing at about 60 mph on my speedo, keeps my rpm's right at 2000 or just under on flat ground. keeps the truck moving at a nice pace. i do have to hammer it to hit a hill, but for the most part my rpm's stay steady at 2000.

*edit, just noticed i replied twice in this thread. duh...

06 2500 35" tires 6" lift super chips programer , 06 35' WW Full water , Gas , SXS , two quads , two bikes , fire wood tools 8.1 miles per gallon average round trip 60-70 miles per hour tow mode 5th gear never 6th !

41' Weekend Warrior, 5 seater buggy and 2 quads inside. 06 F350 Dually, 4.30 gears, 75mph getting 6.5-7mpg. Don't care. It tows awesome.

My father 02 F-350 CC 4x4 7.3 on 285/75/16 BFG AT pulling 34ft next level and 4 quads has gotten a best of 10mpg. Not bad for the weight. Not towing has gotten a best of a lil over 18.

Have an 08 F-450(4.88's) sittin on true 35" tires pulling a 48' enclosed loaded(20K) & get a whopping 6-6.5 to Yuma(fairly flat). Get it in the mountains or a head wind can easily can drop to 5... Yes this is hand calculated & adjusted for tire size. Get at the very best 10 unloaded.

I have a Banks tuner & it is basically useless except for the guages. Once the warrenty expires it will be on to a 210 Sparten tune & an exhaust(DPF delete) & it will easily improve 50%! There are members on this board as well as many people on other sites that swear this is true.

Love my 450 but it gets HORRIBLE milage & is underpowered... Up side looks awesome, pulls BIG loads straight & stable, so even if it never got better it would be OK...

We had a 33tb "bumper pull" that was around 13,500 loaded, pulling with a 2005 Dodge 2500, Cummins, auto, 4x4 on 35" tires and got the best of 10.2 on a round trip to G and back not more then 60 MPH. I think we had a tail wind both ways...

05 3500 crew cab long bed 4x4 duramax all stock pulling W.W. 35ft fifth wheel with 1800lb buggy I get anywhere between 9-11mpg.....

Something ain't right if that's all you get unloaded. Mine gets 17-20 unloaded.

Towing a Sierra (Forest River) 18' trailer with 3 full-size quads, 1 dirt bike, 1 70, 1 pit bike, guessing about 6500' rise and fall each way (adding 50 gal. water after the mountains and dumping tanks before heading up again), 140-ish mile one-way trip, 50-60 uphill/downhill speed, 60-70 flat speed...weighed with the Excursion about 16,800 total weight, probably a bit less with the longbed standard cab F-250.

'94 F-250 460 gasser - 5.8 MPG average over 3 trips.

'05 Excursion 6.0 PSD - 9.2 MPG average over 4 trips.

when it didnt have a camper my 99 cummins 5spd 4x4 would tow a 38 thor fully loaded with quads (little over 14K 5 bikes 4 industrial ice chests, 100 water, 55 gallon race drum, 55 gallon spare water drum blah blah), we could around 11 in the hills and 13 on the flats, No mods at all same tire size as factory... 260K miles and still gets 18 around town...

Box stock 2007 Chevy 4x4 Duramax, 26' WW, 2400lb car, 100 water, and all the other BS, 9-11mpg

1994 frieghtliner 12.7 detroit 33ft 5th wheel and a 16ft flat bed behind that I get between 10 and 12 all day long.

i get a solid 7 mpg towing on a 2000 f250 completely stock truck

I love hoverman's avatar

if you want good gas mileage go buy a hybrid toyota. no matter what you tow your mileage is going to suck. mine personally is a 2008 duramax stock pulling a 40FT 16.5K loaded 5'er and if there is even a hint of wind i am lucky to get 8mpg. it tows it down the road like its nothing so i try not to look at the mileage after a fillup.

i just need a bigger tank. why did chevy think a 26 gal tank was big enough?????????????

Lobo, 8 mpg is GREAT! Really, that is a VERY respectable number for a 40 footer. My guess is that loaded you are considerably heavier than 16.5k Have you weighed yourself?

26 gal. does seem small. was there a Chev. option for a 2nd tank? Seems like 26 + 40 would be reasonable...

Nope. All shortbed Chevys came with 26 gallon tanks. Makes you want to punch babies and kill kittens when you're filling up once every 160 or so miles. Imagine the fun for the 8.1L guys getting 5 or 6mpg? Ugh.

You can get aftermarket tanks that are larger, but are expensive and often reduce ground clearance.

Rockwood the only aftermarket tank that reduces ground clearance is the Transfer flow. The TITAN tank is the way to go. It's lighter and better designed. Made from plastic like the factory tank not metal like the transfer flow. Overall either is a good buy for us short bed guys....i will be buying the TITAN myself, if you are worried about 2 inches of ground clearance at the frame rail though...you must be using your tow rig for some crazy hairy offroading....mide is a street queen unless the Fifth Wheel is on and then it's wash 10-11 in and out...nothing to hairy in there to worry about an inch or two reduction in clearance.

Ah, didn't realize that the Transfer flow was the only one that reduced ground clearance.

As for off-roading, I don't do it either in my truck. I also don't have to worry about getting another fuel tank, since i have a Dodge long bed (34 gallons) with CTD power. I was just pointing that out in case someone didn't know.

My in-laws have the 8.1L, and they've only off-roaded theirs for recovery purposes.

The huge fluctuation from like vehicles in this thread is interesting to say the least. Somebody isnt being honest...

Huge fluctuation in driving habits as well. I get passed by guys all the time going to/from the desert. Some people just want to get there, some people think about fuel mileage/vehicle longevity. I know I usually tow at 50-60mph and try to maximize coasting time, while many others tow at 60-70mph and are on the brakes or accelerator the entire time.

Routes are different as well. SD-Glamis probably uses more fuel than Phoenix-Glamis.

Last weekend was the maiden voyage for the new trailer 35' ww LE and towing from Simi Valley to the High Desert I got 7.5 with my 07 f250 4" lift on 35's 3.73 gears. Trailer has the axles flipped as well. Towed great!