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Diesel Motorhome MPG-- Honest Answers Please

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11 hours ago, rpelatt said:

Thanks Wildebill308. I will try that.

Please report back what your results are. I would use double the recommended dose for the first tank.;)

Bill

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9.9 mpg.  2014 Tiffin Allegro RED 38 feet Cummins 340 ISB/Allison 2000 a I believe - Freightliner, 28+k GVW no toad at speed limit (or 69 in 75 zone).  For what it is worth I am a cruise control nut and will use whenever possible. We are in the middle of our first "big trip" post purchasing our used rig (started with 29k miles and we have driven approx. 1650 miles.)  9.9 includes mostly interstates (40 primarily) from Las Vegas to more scenic routes (NatchezTrace Pkwy for 130 miles whith speed limits starting at 40 mph with majority at 50 mph - I ran at 52 mph - TN to MS/AL.  While I am not obsessed with mpg, i do appreciate finding my own sweet spot (cost/comfort/time/monitoring for changes in performance).  Because OP wanted good info to help guide decisions (just like I used these forums to help me with my decision) I will add that our decision to purchase diesel pusher was a great one post a previous recent rental of V10 gas 39 footer where conversations were difficult to have while driving due to noise ( or to mention smoothness of current ride and torque/power).  Best of luck as you make your decision.

 

 

 

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16 hours ago, WILDEBILL308 said:

Please report back what your results are. I would use double the recommended dose for the first tank.;)

Bill

Will do. Leaving on a 7500 mile trip Oct.1. Really looking forward to see average mpg. 

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2009 County Coach 45ft; 50,000#; 500 ISM Cummins, pulling a GMC Arcadia 4 down.  NOTE: Onan and Aqua Hot always in operation when we are going down the road, so that will also burn a bit more fuel.  I never shut to motor down until we are at the end of the route or day.

Average 6.5 MPG over the last 12 months of flat, headwind, tailwind, hilly and stop and go.  They key is speed.  We are capped at 65 miles per hour tops with the GMC, so we are at that speed or less.  Your mileage may vary!!  :) 

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Your Aqua Hot will not burn any diesel unless the burner is on...which it does not need to be on unless very very cold outside.  When on it burns 0.4 GPH.

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Since I also run with gen on, I turn my AH off, get plenty of hot water from engine.  I turn mine to diesel for showers, electric for dishes.  Only had the AH on one time for furnace while driving, got caught in Ice and Snow in Utah, 3 years ago! :( 54,300+/- pounds + toad, 45 foot American Coach.  6.2-6.4 avg. mpg.

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We've only used our AH once on the road once also.  Left home heading south in Jan, 8 degrees, wind blowing hard.:(

Carl...are you sure you are that heavy?  My Eagle 45' is 49k GVWR...maybe that 54k includes the toad?

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9.7 mpg with our FRED 2016 Seneca Super C running a 340 ISB/Allison 2500 and pulling a Wrangler between 60 - 65 mph on flatlands. Allison is currently operating with 'economy' shift schedule but I'm having it flashed to 'performance' schedule soon. Can't beat the ease of powertrain access on a Super C diesel.

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Our previous coach, a GM 4106 averaged about 7 mpg. Mostly kept to 62 mph. That coach had Detroit Diesel 8V71 with Allison 730 automatic.

Our current coach, a 1974 GMC 4108a averages about 8.5. Same speed, but the 8V71 on this one is mated to a 4-speed manual transmission.

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FIVE.  Big difference between GVWR and actual weight with people and gear and toad!  My toad 2013 Jeep Wrangler, with half tank of fuel & survival gear, is 4,400+ pounds!  No, it's far from stock. :o  Since taking Linda onboard (she is shedding more and more carry on weight), I weight it this June, way over GCWR.  Went back to house and she took out all the rocks (she makes Jewelry), tumblers and rock hound equipment along with 3 arm loads of clothing, 2 covered patios 12' X 12', 3 full tool boxes...that shed over 2,400 pounds!  Now, she understands that what she carries in her 40' Phaeton DP, does not fit in my 45'! :(:lol:

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Trip we are on currently: Conroe, TX to Ventura, CA.  Two fill-ups. Toad = 2016 Jeep Grand Cherokee = curb weight 4,500 lbs. Route Interstate 10.

Conroe to Fort Stockton TX.  5.9 mpg.  Average speed = 65 mph.  Generator running 50% of the time.  Slight headwind.

Fort Stockton TX to Tucson AZ.  7.3 mpg.  Average speed = 65 mph.  Generator running 70% of the time.  Quartering tailwind gusts.  Crossing Continental divide at 4500' ASL.

Tucson AZ to Ventura CA.  6.8 mpg.  Average speed = 60 mph (65 through Arizona & 55 in California).  Moderate crosswinds.

At 65 mph I run in 6th gear unless on hilly terrain = ~1350 rpm.

At 55 mph I select 5th gear unless terrain dictates differently = ~1500 rpm

Gross weight on coach is 34,600 lbs.  I'm loaded to ~32,800 lbs.

Cummins ISL 400.  Allison 3000 series.

Tires: Front = 110 psi. Rear duals = 105 psi

Blake

 

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Our 40 ft Tradition, with 330 hp Cummins, 3000 trans , 295 75 22.5 Toyo tires, traveling light, avg speed,  gen running 50% of the time55 mph got 10.8 mpg. At 60 mph got 10.6 mpg on trip from Detroit to Jasper, Alberta.

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18 hours ago, roadster27 said:

Our 40 ft Tradition, with 330 hp Cummins, 3000 trans , 295 75 22.5 Toyo tires, traveling light, avg speed,  gen running 50% of the time55 mph got 10.8 mpg. At 60 mph got 10.6 mpg on trip from Detroit to Jasper, Alberta.

What year is your coach? Were you towing?

Bill

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Admittingly, I have not read all of the threads/replies to the OP's post...

Motorhome = 2017 Newmar 45DP / Spartan K3 / Cummins ISX15 (600hp)

Motorhome Length = 44.11"  (w/installed Hydralift + Tow Vehicle OAL = 70' 3")

GCWR = 74,000 (we run at the mark, loaded).

Normal Average Interstate Hwy Cruise Speed = 65-MPH

Towing = Jeep SUV @ 5,000 + Garia LSV (Golf Cart on Lift) @ 2200 lbs (LSV + lift weight combined)

Cumulative Mileage Driven to date = 12,900 miles (still not "broken in")

Average MPG (all road types combined) = 6.7 MPG

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This post has run for quite some time now.  I may be wrong, but guessing about 10% of all replies are honest answers...Rick, your one of them!

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15 hours ago, hream said:

Winnebago Journey DP  -2012 with Cummins 360 towing a Jeep Cherokee - last 21,579 miles average 9.03 MPG

Welcome to the forum. Do you run DEF in your coach?

Bill

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I noticed that there are not any new post on this for quite a while but I have a question about performance chips and am hoping to get some feedback from people who have really used them.

I have a 2006 Tiffin with a Cat C7 350hp. I have read most of the post here about mileage and agree that there are a lot of conditions that affect it but I would like a little more power when needed and be able to dial it down for better mileage when I can as well. I see ads on these all the time and know most of it is BS but would like some honest answers please.

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We bought a new 2018 Fleetwood Pace Arrow 36U last week in Hammond, La.  Driving it back to Deer Park a suburb of Houston, Texas around 300 miles we got 8.8 miles per gallon running the generator and pulling a 2016 Chevrolet Colorado.  We were happy with this result.  Our old 2014 Coachmen Mirada  averaged 5.8 miles for the four years we owned it.

We are leaving this coming Saturday for Shawnee, Oklahoma and then to Kansas and other parts of Texas so I will be looking forward to seeing what the miles per gallon will be.

Jaime

 

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We have a 2009 Gulfstream Tourmaster Consellation 45g. With a 425 hp Cummings, Allison 3000 transmission, weight app x 52000 lbs towing a Jeep Grand Cherokee @ 4700 lbs. I usually drive 64-67 mph and get on the average 7 mpg. Now you have to factor in we live in Florida. I am more concerned with what the trip costs me per mile than the fuel mileage. Two years ago it cost me $ 1.65 per mile, but fuel prices were much less than they are now. That did not include the yearly service on the Motorhome. There are so many factors to the fuel mileage issues like elevation, temperature, water vapor, ect.  Like my son told me, Dad drive it or park it if your going to whine about fuel prices.

IMG_0214.JPG

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Like everyone else we've heard of fantastic mileages. Even had one day with 20mpg+ with a 70 mph tailwind Oklahoma into Kansas.

About 7mpg+ running with the rest of the traffic including some hills, some mountains.

We only have a 35 hp C7 diesel and pull a 4200 lb Ford Edge.

When we pulled our Saturn we got a 1/2mpg better maybe. Ours does not use the blue juice.

 

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