Does this make sense? MPG?

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Sailorkane

Well-known member
Joined
Sep 30, 2015
Posts
290
Location
Tampa, Florida
Just took our new (to us) 39' Journey on the first trip.  Ran for 580 miles and measured fuel consumption.  I am well aware of the difficulty in measuring MPG in one run--chances of error in filling tank, writing down something wrong, head or tail winds, hills, etc.  But I'm slightly pleasantly amazed at the MPG we measured.  Flat ground, 95% hiway driving, 2003 Journey with Cat 3126 330HP engine and Allison in economy mode, very little idling, no gen run.  Tires properly inflated, pulling 3000# sedan toad, driving about 65mph on cruise, pretty sure I properly filled tank at beginning and end.  580 miles and 50.1 gallons.  Or 11.5MPG.  I am not sure what I expected, but certainly not over 10 MPG.  Is this reasonable?  Next distance run is not until January.  Our last motorhome was a gas adventurer and averaged probably 7MPG.

PS:  admin, if this belongs in another forum, no problem.
 
As you said, only by taking MPG measurements over time will you be able to get an accurate reading. In the end, using the parameters you mentioned, I'll bet you're going to see closer to 8 MPG, but hey... nothing wrong with enjoying the moment! :)

Kev
 
The 3126 is certainly capable of that, but you probably won't average that high.  My Trip Tek engine monitor says I hit 10.1 for a single day run a couple months ago [with a larger engine and heavier coach] and I loved it, but wasn't surprised when it dropped down to 8.6 the next day. Sometimes the stars align and everything works near perfectly!  I hit the high mpg when the temperatures were mild, traffic light, and the run downhill (descended about 1800 ft over 188 miles).
 
If you are smooth and easy on the throttle and use the cruise a lot, you can certainly get upwards of 10mpg. We have a 35ft Journey with an ISB and consistently get around 11mpg +/- 0.5 if I keep the speed set at 65mph (towing or not). Only the cold and a headwind knocks it down.
 
We have the exact rig as the poster above and consistently get 8.5+/- driving as he describes or slightly faster.  Maybe he's a more careful driver, but I would expect more like 8 to perhaps 9 on good days.

Ernie
 
Gary RV Roamer said:
A little head or tail wind can make a huge difference, as can a few mph of average speed.
Exactly. We've run into headwinds that cut us back to 5.5mpg or a tailwind that will take us to the 9mpg range. Terrain also makes a huge difference as does altitude.
 
Ernie n Tara said:
We have the exact rig as the poster above and consistently get 8.5+/- driving as he describes or slightly faster.  Maybe he's a more careful driver, but I would expect more like 8 to perhaps 9 on good days.

Ernie

Ernie, I'll bet that I run a few extra psi in my tires versus what you do. Less rolling resistance, but at the expense of a smoother ride. It has never bothered me.

Regarding the "slightly faster", I notice that fuel economy drops off if I go just 3 mph faster. 64mph is the sweet spot for my coach.

Dave
 
I generally run one or two mph below the speed limit so I don't doubt I could kilk another mpg if I were careful. My tires are about five psi above manufacturers recommendations.

Ernie
 
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