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Discussion Starter · #1 · (Edited)
I would like to hear what kind of fuel mileage you are getting when towing a load (and the size\weight of the load). I have a Early 2007 (LBZ) crew cab 3500 Dually with the 6 Allison 4wd 3.73 rear that is about 7000 miles old and I feel my fuel mileage is way too low. I am in the trailer business and I travel a lot pulling heavy goosenecks. On recent long highway trips, running empty at around 70-75 I would get about 13.5-14 MPG. When I hook up to a small trailer (18ft dual axle lowboy empty 2000lbs) It will drop to 11MPG. When I hook up to a larger trailer (25'-30' Dual tandem dovetail Gooseneck 5500lbs empty) It will drop down to 8-9MPG. If I put my tractor up on the trailer (Older International 656 about 6000lbs + 5500lbs of Trailer = 11500 Total) It can drop in the range of 7-8MPG. My alltime worst was yesterday, (44' gooseneck with a 40' gooseneck on top of that for around 15-18,000lbs total) will drop my mileage as low as 6.5MPG in some hills and 8MPG on smooth ground. All of these figures are for EMPTY trailer (except the tractor example). I expected better than this when I spent 45K on a truck. Is this normal???
 

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have you changed your fuel filter since you bought it? You may not like it, but try driving no faster than 60 or 65 and see if it helps your mileage. I get about 10-14 mpg towing a 24' enclosed snowmachine trailer (car hauler) with 4 mountain sleds in it. that is winter and mountain driving. In the summer, I get 17-19 empty driving about 70 mph (that is 2000 rpms for me). With all the new emissions stuff on the new trucks and ULSD, that could be causing it your low mileage. I have a first generation engine, so I have a totally different animal than you. Very few people see the 20 mpg mark that I have often heard. The best I ever got with mine was almost 21 with stock tires on. Right now with the winter driving and super cold temps(-20 to -30F) up here, I saw 12 mpg unloaded going to fairbanks and back to eielson (about 25 miles one way). I did idle the truck for probably a total of 45 mins on this tank. I have heard that people are unhappy with the mileage they are getting on the new trucks. You might want to go to the dealer and see if there are any software updates for your truck. Other than that, I don't know what to tell you.
 

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That sounds about right from what ive heard. Ive got a friend with an 06 dually and his average is 7 or 8 mpg. 90% of the time hes got a gooseneck full of cattle behind him.

BTW, welcome to the site.
 

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Biggest load i everhauled was a 73 chevy with a 6" lift and 40's on it @ 6000lbs, on top of a 22'over the axle adjustable beavertail Cornpro trailer @4700lbs so a big high (lots of wind resistance) Load weighing 13k on a 350 mile trip i avg.13mpg with a 90 hp efi tune loaded!!!
 

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I pull a 28' toy hauler, loaded up with gear and bikes it is about 12,000lbs. I'm pulling it with a stock '06 2500HD w/ LLY, mostly mountians and 65+mph, I'm getting 8-9MPG (I can still pass anyother truck pulling a load uphill) Not bad all things considered, I'm hoping to see some increase after some mods.
 

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I haven't pulled any loads yet (plan on pulling the wife's SUV through the mountains when I move to Washington next month @ 5000 ibs.), the truck has only 650 miles on it. On the first two tanks I was averaging a hair under 16 mpg, and most of its city driving. Just food for thought...my dad who is a retired truck driver said that if the Duramax is tuned slightly wrong it can cause bad gas mileage. I thought he was smokin crack, but maybe there is something to it, never know.
 

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With all the new emissions stuff on the new trucks and ULSD, that could be causing it your low mileage. I have a first generation engine, so I have a totally different animal than you. I have heard that people are unhappy with the mileage they are getting on the new trucks. You might want to go to the dealer and see if there are any software updates for your truck. Other than that, I don't know what to tell you.
The trucks built before January 1st will not have the new emissions or ULSD on them. My dad went looking to buy a new one, and was told by the dealer that if he wanted a new truck, he better get one quick before they put all the new emissions equipment on. He ended up ordering one out about 3 weeks ago...on the condition that it must be one built before January. I was surprised to hear that his new truck will be in by the first week of December! And I always thought it took longer to have a truck built to order!

As for low fuel mileage, remember your engine is not even fully broken in at your current mileage. Look for your numbers to increase as all the parts "get to know" each other!
 

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I would like to hear what kind of fuel mileage you are getting when towing a load (and the size\weight of the load).
Recently I have bought 2 new identical trailers, 28' high profile van trailers. I picked up each of them about 10 days apart. Each one was towed from Springdale Arkansas to Las Cruces New Mexico. The first trip I drove a Ford F-350 V10 at about a 70 MPH average speed and I got about 6.5 MPG (computed). On the second trip I took a 2005 Chevrolet C-3500 Duramax, I got about 8 MPG (computed) at about the same speed (maybe a little faster :))

The Chevy had a performance advantage, but all in all both trucks performed well. Considering the 50 cent a gallon difference, the cost of operation was very close, possibly advantage gasoline, (I dont like it, but this seems to be reality).

I am involved in a family bussiness that has been utilizing 1 ton truck and trailer combinations since 1974, and all in all the numbers that you have posted seem reasonable to me, albeit I would expect to see your mileage increase slightly as the truck begins to break in.

There are a lot of claims made about mileage that I find difficult to believe because there is really no magic bullet, when towing trailers, it takes a certain amount of energy to do certain amount of work, with usually only small diferences due to certain efficiency issues and the related issue of emissions. It is my opinion that the main issue when it comes to fuel efficiency, is the driver and his or her driving habits.

You will hear alot about the weight that a truck pulls when trailering, but it is my opinion (and experience) that the primary concern is wind resistance. (ie: energy lost pulling a heavy load up a hill can be partially recovered going down the other side of the hill, energy lost to wind resistance is never recovered, (unless you always drive downwind:tease )

If you want to drive 75 when trailering, (I do), you need to be willing to pay the price at the pump. For bragging rights I could have coaxed more mileage out of both of these trucks by moderationg my driving habits, but whats the fun in that?
 

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The trucks built before January 1st will not have the new emissions or ULSD on them. My dad went looking to buy a new one, and was told by the dealer that if he wanted a new truck, he better get one quick before they put all the new emissions equipment on. He ended up ordering one out about 3 weeks ago...on the condition that it must be one built before January. I was surprised to hear that his new truck will be in by the first week of December! And I always thought it took longer to have a truck built to order!

As for low fuel mileage, remember your engine is not even fully broken in at your current mileage. Look for your numbers to increase as all the parts "get to know" each other!
Actually the ULSD fuel is out and being used in some stations depending on where you live. Just having the cat and egr on the trucks decrease the MPG. My truck doesn't have any of the emissions stuff on it...never came with it...it's a LB7. I do agree with the mileage not going up at low miles. My truck is just getting broken in at 42000 miles.
 

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Actually the ULSD fuel is out and being used in some stations depending on where you live. Just having the cat and egr on the trucks decrease the MPG. My truck doesn't have any of the emissions stuff on it...never came with it...it's a LB7. I do agree with the mileage not going up at low miles. My truck is just getting broken in at 42000 miles.
ULSD...got my acronyms confused. To many 3 and 4 letter terms out there now! Anyways, I do not believe we have seen the ULSD fuel here in Wisconsin yet.
 

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Are you guys serious on the fuel milage towing? I am buying a new truck, and I'm seriously considering a chevy/gmc. However, I currently have an '03 dodge H.O. cummins 6-speed, 1-ton srw quad cab 4x4, and when I pull my 36' toy hauler it gets 11-14 mpg, depending on wind, terrain, etc. I have driven a '07 chevy 3500 CC 4x4 dually and really liked it, but I need to know its gonna get better than 6-8 mpg pulling my camper. Please dont take this as a slam, and I'm not a "troll" trying to stir things up. I'm just tring to make an educated decision on my next tow vehicle. Thanks in advance for any input.

Cat Cracker.
 

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I say that if you truck now gets that good of mileage towing your camper, you should stick with it. The EPA has really screwed things up by making these trucks with stricter emissions. With the lowering of compression in the engine, there was a loss in mileage...couple that with all the emissions stuff on the new engine and ULSD....I would say that you would be lucky to get 12 mpg towing your 36' camper. I don't know that for a fact, but I find it hard to believe that you could much better mileage with a new truck. Your dodge has a inline 6 right? You are adding 2 more cylinders to burn more fuel with the GM. I can't promise you would get much better than you already are with your dodge. I know of one guy that bought a Chevy with the LLY engine and he was struggling to get better mileage than his other truck with a 454 in it pulling his 40' toy hauler. Don't get me wrong, I love the GM trucks, but the EPA is really screwing us over by making more strict emissions. I would go over to dieselplace.com and read what they are saying about the new engine and mileage they are getting while towing. I know I was disappointed with the mileage I got after hearing the claims that some people were getting. Well, I found out, my buddies claims weren't fact....I got better mileage than he did with his 7.3 PSD.
 

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The "new" engine isn't out yet. GM will not be putting them into trucks until January 1st. Any 07 built before Jan 1st will also not have all the extra emissions that are mandatory in 07 (07 being calender year, not build date or model year). I would expect 06 and 07 (pre-January) to get comparable mileage to your Dodge (depending on how you drive) seeing that the General put a 6 speed Allison in. Just remember that a brand new truck will have lower initial mileage until the engine is "broken" in. I can't say that I have towed a huge trailer with my truck. A 20ft open car hauler with 8 or 9 sleds is all I have first hand with. But with that load I still averaged 16 mpg. That was with a bone stock truck, traveling 80-85 down the interstate. My truck is an 02, so mine is still a 5 speed Alli. If you were to keep the speeds down (keeping the RPMs down too), I am sure 18 mpg towing at 65-70 would be easily reachable.
 

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Kawtipping,

The newer LLY and LBZ aren't getting great mileage like the LB7 did. Even with the 6 speed they aren't getting very good. Go read on dieselplace.com. Most of those guys are lucky to get 16 unload with a dually. Now to ask you....when you calculate your mileage, do you hand calculate it or use the DIC? I have an 04 with the LB7 engine and I never got 16 mpg towing. I towed a boat 300 miles round trip and I was running on fumes when I got back. (I never got above 70 mph since I was driving up the Haul road) I got 13 mpg on that trip with my truck running the stock 245s. The best I have gotten since was last year going to Arctic man pulling a 28' camper....I got 14 during that. Besides, running 80 down the highway is running nearly well over 2000 rpms with stock tires. The mileage on these trucks drop of dramatically over 2000 rpms. Were you going down hill with a tail wind? I'm sorry to sound skeptical, but if I didn't actually ride with you, I can't believe that one. I have found out most people either 1 don't calculate their mileage right, or 2 don't fill the tank up to the same spot as when they started. The LLY and LBZ, they lowered the compression from 17.5:1 to 16.8:1....that accounted for a mileage loss even though the 06 one had a 6 speed allison in it. BTW, I do get about 18 mpg empty and when I tow anything over about 2000 lbs, the best I get is 14 with my current set-up....my speedo is corrected for tire size verified with GPS.


On edit, I am just trying to give the best accurate info for people to make their own decisions. I don't want to inflate the mileage claims that some people have and have someone get pissed when they don't get anywhere close. Is it possible to get higher mileage towing....sure, but it is unlikely to see those numbers on a regular basis especially with a dually like Cat Cracker is looking at. I have driven my truck at all speeds and light accelleration to see what kind of mileage I get...no matter what I do I normally get pretty close to the same. So, I gave up and just drive how I normally do. Most of my driving is below 70 mph. I bought the truck to drive it and tow things. I get better towing with my truck now than I ever did with my 2001 silverado 1500 with the 5.3 gas sucker. That is all I care about.
 

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Figured out by hand of course. The 02 did not have a dic. Mileage divided by gallons added. Always fill the tank until foam will not allow me to add any more. My trip with the trailer was a 5 hour freeway jaunt with one stop between (the 2 other trucks needed fuel...both Dodges) Milwaukee and Minneapolis. Like I said, everything was stock right down to the rubber. It may have helped that the truck had the highway tires, and not the on/off road option tires.
 

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Sound right to me. I just got back from Missoula Montanna the other day pulling an enclosed 40ft gooseneck for 3000 miles and I averaged 8.3 full going there and 9.6 on the way home. Granted i was going 75 / 80 mph the whole time.
 

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Thanks for the information. I still haven't decided yet, and I know I'm running out of time before the "new" motors are here. (Dodge has a "new" cummins that is 6.7 liters and a diesel particulate filter) So, I don't want either of those. I like the interior and features of the chevy, and the ride is better, (IFS vrs. solid axel) the motors are real close (IMO) I like the allison way better than dodges 48re. (thats why I have a 6-speed:gearjamin ). Ofcourse the mega cab is huge, but I can only get a short bed, which is ok, I just have to get a different hitch. I have 5 children, so interior space is important, and I need an auto, because someone has to sit in the front seat with us, and the shifter gets in the way. Thanks again for the info, and I'm sure I'll have more questions soon.

Cat Cracker.
 

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I did a recent 1300 mile unloaded trip at 75mph on the interstate and had a 18.2 mpg average hand calculated with the Edge EZ on #1. When towing my Jayco 32 foot travel trailer which weighs 9200 lbs at 65 mph, I average 11.2 mpg hand calculated.
 

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I have a 01 ext. cab 4x4 short bed dmax. I recently pulled a 24' gooseneck flatbed trailer that maxed out at just under 14k. The load was two rows high of 60" round hay bales. I was pulling into the wind loaded and ended the day at just over 10mpg, with a bullydog power pup. My truck has a 24 gal. fuel tank and I used just over a quarter tank. On the second trip I used my moms 05 dodge cummins crew cab short box auto. Everything was the same, (this load was 200lbs less) she has a 35gal fuel tank, and it took almost half a tank. Didn't have time to compute the mileage. her computer said anywhere from 6-8, and her truck has 25,000 miles on it.
 
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