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Old 11-17-2011, 04:17 PM   #1
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OK. One last query for this week.

What gets better mileage for a motorhome?:

a) Ford Triton V10,
b) GM Workhorse/Allison,
c) Ford diesel
d) Cummins diesel,
e) Caterpiller diesel

I have read discussions about the Ford and GM, but can't seem to find much on the diesels. I am also aware there are different horsepower ratings for the diesels depending on the year and coach.

Just looking for a generic MPG from those who have or had them.

Curiosity is running rampant!


wife, 3 Scotties and an African Gray parrot - and they all terrorize me!

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Old 11-17-2011, 04:25 PM   #2
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The driver can make 30% difference alone. So each would have to be the same make, model, weight, driven over the same course for many miles (Cummins says 144,000 miles) by the same driver.

2009 45' Magna 630 w/Cummins ISX 650 HP/1950 Lbs Ft
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Old 11-17-2011, 04:34 PM   #3
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I understand that.
I'm looking for comments like " We have a (*) with a (*) and we get (*)".

And I am talking both class A and class C.

I have of heard some 35 ft diesel pushers getting almost 15 MPG. Having worked on both Cat & Cummins big rigs, I find that hard to believe.
However, if true, that beats the puddin' out of the gassers of about any size.

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Old 11-17-2011, 04:43 PM   #4
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Hi gaugeguy,
For me and 81K miles the very consistent numbers are:

Coach and toad are 37K lbs.
Cummins ISC 330 HP
Cruise at 60-62 MPH
RPM is 1800
Fuel MPG is between 7.5 and 8.5 figured every 1K miles and for the entire trip. For me, fuel mileage depends on wind and terrain.

One can also determine fuel mileage the same as the railroads do. MPG per ton of weight moved down the road. That calculation gives me around 128 MPG per ton of weight. Cost is the same, but it sounds better.
2005 Newmar KSDP 3910 + GMC ENVOY XUV 37K lbs Moving Down The Road
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Old 11-17-2011, 04:47 PM   #5
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8.1 workhorse gasser no upgrades. I average about 8mpg.
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Old 11-17-2011, 04:50 PM   #6
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also have the 8.1 workhorse Southwind with toad. 7.5 to 8 mpg
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Old 11-17-2011, 05:29 PM   #7
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They are all around 8 mpg, give or take 0.5 depending on driver, terrain, and motorhome size/weight/aerodynamics. The diesels will move a large heavier coach with the same mpg as the gassers with a smaller coach. If you were to get a small diesel in a coach size similar to the gas model, e.g. the Freightliner FRED vs a similar Workhorse or Ford chassis, the diesel would deliver about 15% more mpg, largely becasue the fuel has about 15% more energy per gallon than gas.
Gary Brinck
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Old 11-17-2011, 05:44 PM   #8
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I'd say anyone who tells you they have a 37 ft diesel MH that gets 15 mpg needs a math refresher class. My 39 ft DP pulling a Jeep gets anywhere from 7.5 to rarely 8.7 depending on wind, temps, and terrain. I usually drive 62 mph.
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Old 11-17-2011, 07:57 PM   #9
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I agree. There was another fellow swearing he got 13.1 MPG with his 32 foot on a Cummins chassis.
I think not.
Gas @ $3.50 gallon x 75 gallon tank = $263 per tank, then 75 gal x 8 = (roughly) 600 miles / tank, then that looks like 43 (+/-) cents per mile, just to drive.

So about 49 cents per mile with diesel.
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Old 11-17-2011, 08:15 PM   #10
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2011 Ford E450, V10, 3700 miles, 27' Phoenix Cruiser (see signature).
Avg. MPG is 9.4 over the 3700 miles.

Before that a 36' Alpine Coach w/330 ISC Cummins towing a Ford Edge.
Avg. MPG was 9.3 over 27000 miles.

All by acurate calculations (at least by speedometer on E450 & Silverleaf in Alpine).
Bob (Squidly Down Under) & Peg - 2013 Ford Focus pushing a 2011 Phoenix Cruiser 2552S
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Old 11-17-2011, 08:20 PM   #11
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Were all going to lie about what we get anyway. Cummins ECM stores what it actually gets. I thought I was getting 7 but the ECM says 6.8. That's the average over 600 hrs.

500HP Cummins ISM in a '06 Newmar Essex running 70mph pulling a 2010 Ford Explorer.
60MPH 8MPG 68MPH 7MPG 72 MPH 6.4MPG.
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Old 11-17-2011, 08:42 PM   #12
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Snowbird trip beginging 10-14-2011 to date=beginning odometer reading 18950. Last fill at 21441. total fuel used 274.6 gal diesel. Cost $1,035. Figure out to be 9.071 mpg. $.415 cost per mile.
2003 HR Ambassador 315 cummins with Banks preformance system and with F-150 standard cab 2wd man tran toad

We bought the coach a year ago and I have more extensive records from date of purchase and odometer reading 5758 when we bought it if you are interested. Totals prior to odometer reading 18950 would be without a toad.

I normally travel at the posted speed limit unless speed limit is over 65 (freeway speed). I tend, in the case of freeway driving, to adjust speed to tack reading and hold it to 1500 rpm which equates to 63/64 mph.
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Old 11-17-2011, 08:51 PM   #13
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Just drove my 46,000 lb Monaco Signature with a 14 liter (850 cubic inches) Detroit diesel down from Maine to Atlanta at 62 mph and got a solid 6.2 mpg average for the whole trip towing a Jeep Wrangler. Figure out what that cost me lol.
Mike Canter
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Old 11-17-2011, 08:58 PM   #14
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I'm averaging around 8-8.5. Thats with 8 people and supplies loaded for said group. Also with 8 tires on the ground. I have seen big differance keeping foot out of it. I try to stay 60-63 depending on hills.

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