Poor Economy or Not Bad?

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May 23, 2006
  I recently purchased a 2005 29' Dutchmen Lite TT.  It weighs appx. 5000 lbs. empty.  I'm pulling it with a 2003 Chevy Silverado 1500HD with a 6.0L and 3.73 Axle Ratio.  I have a topper on my truck as well.  I pulled the TT appx. 200 miles over Memorial Day and averaged 5-6 mpg.  It was in Tow/Haul Mode.  Does this sound reasonable to you?  I had just changed the oil, air filter, etc. on the truck.
  I'm getting ready to head out west next month for appx. 1800 mile trip, so this could add up quickly.  I'm wondering if it would advantageous to upgrade to a Duramax diesel or other diesel truck.  I've pulled a 24' flatbed for a previous employer with a 2500HD, 6.0L and 4.10 and got appx. 10 mpg with a trailer loads of 7000 lbs.  I wasn't as high as this TT...
  I appreciate your input as I'm new to RVing.  My current truck has plenty of power, just concerned about the economy.  Thanks in advance.

Take care,

That milage is a bit less than one would expect with the trailer weight you listed.  I wonder if maybe tank wasn't full before you started your trip and you didn't yet get an accurate milages figure. 

We just returned today from a trip between Phoenix and Ridgeway, CO which involved a fair amount of mountain driving.  For the whole trip of 1676 miles of which about 1080 was towing the TT (and the rest was driving the backroads), we averaged 11.2 MPG.  My towing milage for the first 540 miles, between Phoenix and Durango, CO I averaged 9.2 mpg.  All the towing was in the tow/haul mode.  When climbing a long, steep grade, the truck had no problem maintaining speed but I don't like to see (or hear) the engine go much over 4000 RPM, so I tend to slow down on the climbs to keep the RPM under 4000. When I just drive the truck without towing on the highway, I get 16-18 mpg.  I have a 2005 Dodge, 5.7 Hemi, with a 3.92 rear end.  My trailer weighs 5600 lbs empty and I didn't carry any water in the tanks on this trip.  I generally drive about 60 MPH on good highways and 55 MPH on the secondary roads.  5 or 10 MPH makes a big difference in fuel economy. 

Before I made any changes I would check mileage over several consecutive fillups.

As was mentioned you don't always get the same level when you fill but also speed, road grade, wind, and traffic all affect the mileage you will get.

Yes, 5-6 is low. I would have expected 7.0-8.5, but you didn't mention your typical speeds and that has a big effect. Your best mpg wil be at 55 mph. Driving habits also are a big factor, You can improve economy a lot by acellerating slowly and anticiapting stops well ahead of time, so that you do not brake hard.

Yes, the diesel would be much more economical on fuel.  And it has a better transmission too. Probably in the 11-13 range.
  Thank you for your comments.  We had another outing over the weekend (200 miles).  According to my driver information center, I got 6 mpg again on the first tank.  I verified this with the trip meter as well. 
  I specifically used the truck for pulling only, as we had our minivan as well.  The trip was a little "hilly" for Iowa, but nothing like mountains.  I typically drove 60 mph.  I'm pulling in D with the tow/haul mode on. 
  I did pull it to the destination with the fresh water tank full.  I don't know if this will make a big difference.  I'm going to give it a shot out west and see how it does on the interstate.  Maybe next year, it will be time for a diesel.

Take care,
With the price of diesel, the cost of a new truck with a diesel and the minor gains, you would have to pull with it for the next 15 to 20 years to come out ahead.  Now if you want to talk about torque and power, that is another thing.
? ? ?I have a GMC 2500HD 6.0L 4X4 with a Hypertyech program and Flowmaster exhaust.I pull right around 10,000 lb 32 foot fiver and am averageing 7mpg. One thing I would suggest is pull in 3 instead of D.This will run your rpm a little higher but in the long run you will do better on economy. It 's a simple as it takes less pedal to make higher rpm which makes better torque and horsepower with less fuel.Sounds crazy but I have tried everything trying to milk mileage out of a gas burner. This is also better on the transmission and will run a lower trans temp.(my truck has trans temp gauge so I monitor that).Good Luck on the diesel I have been looking at the same and for the price difference of the diesel option you would need to drive it for approx 95,000 miles to break even on the price difference.
Something else to consider is your use of cruise control if, in fact, you do use it. While it's nice to cruise along at a steady clip without your foot on the gas pedal, the engine and transmission may be up and down-shifting more frequently than necessary. Experience will show that letting it slow down a bit when climbing hills can save a significant amount of gas and reduce wear on your tranny. Yes, we all know that Iowa doesn't have a whole lotta mountains, but you get the picture ;D

Correct tire pressures are also important for best fuel economy and safety.  If you're unsure of what it should be, have both the puller and the pullee (truck and trailer ;)) weighed, and using tire manufacturers recommendations, inflate accordingly. Remember that both right and left tires on the same axle should be inflated to the same pressure. If the rearmost axle on the trailer calls for, let's say 65 pounds on the right and 70 pounds on the left, inflate both to the higher of the two (70 pounds in this example). Same with the front steering wheels on the truck. Even though they are on separate axles, they are considered to be on the same axle and should be inflated equally.
That MPG hurts. I pull a 37' FW (Empty 13,000Lbs). Just finished a 3 week vacation (Memphis, TN to Austin, TX, back thru Memphis to Gatlinburg, TN - then home). Just shy of 3000 miles and averaged just under 12MPG. Pulling with a full tank of water doesn't help and is not needed unless your heading someplace where you know that you'll be dry camping. Run with just enough water to get by (I only carry 5 to 6 gallons), but that still shouldn't have dropped your milage that low. I don't use cruise so the truck isn't trying to keeping going 65MPH up hill, let it slack off. As my truck has a boost guage, I do my best to keep it at 15Lbs boost or less, even when climbing .. so I slow down to 50 on upgrades, but then it's a vacation with no particular place to be at any given time.

Well.  I definitely learned alot from your suggestions.  I was pulling in D with the Tow/Haul.  And I was using cruise control.  I did bite the bullet and bought a new Duramax this week, so I'll be going to CO next week with it.  I was just disgusted with the MPG of the 6.0L, but it was probably due to my driving habits.

I'll keep you posted.

I don't think there is any problem with using cruise control when towing unless you are getting a lot of shifting. I used it extensively on my last trip in tow/haul mode after I got out of the mountains and onto fairly level terrain.  I feel that using cruise control provides better milage than I do under normal driving.  When I sense that it going to shift up and down using cruise control on uneven terrain, I go back to the pedal again. I would like to hear what others say.  When do you use cruise control, when don't you, and are there some of you that never use it?
I seldom use it, except on flat terrain and light traffic as are often found out West.  Even in rolling hills, cruise will cause downshifts trying to maintain speed on smalll upgrades. Depends, of course, on your gearing and engine.

So yeah, cruise control is for cruisin'.    Traffic or hill country ain't cruisin'.
This is related to the fuel economy thread above (didn't want to open a new thread just to ask)...

As I read these posts and ponder a 1500 (1/2 ton) versus 2500 (3/4 ton), I began to wonder something.  Could a 3/4 ton truck actually achieve the same or better fuel mpg than a 1/2 ton truck since the 3/4 ton truck won't have to work as hard to pull a given load?  With the possibility of $5/gal gas over the next few years, I'm more concerned with mpg than with initial purchase price of the tow vehicle.

On my first trips with a Dodge 3500 Maxi class b,  I set the cruise at 65.  I got 11 to 12 mpg over 2500 miles twice.  Then I attempted to limit downshifting by dropping out of cruise whenever I thought it might downshift.  The milage varied from 13 to 15 mpg.  I installed a vacuum gauge  and now switch to the pedal whenever the vacuum drops below 5.  I have been averaging 15 mpg,  I even got up to 16 on a level stretch.
Where did you install the vacuum gage tap?  What do you do other than shifting out of cruise control when pressure drops to 5?  Do you back off on the speed to keep from down shifting?
I found a vacuum hose connecting directly into the manifold, I think it is used for heater controls.  There is a check valve to maintain vacuum when under high throttle settings.  I put a "T" in the hose between the manifold and the check valve.  Yes, I do slow down.  I simply maintain the vacuum at about 5 pounds using the throttle.  If the RV slows down enough to downshift at that pressure it works for me.
I may have to give that a try.  You got a big percentage increase in fuel economy with that procedure.
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