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Topic: mpg on diesel?

Posted By: JenniferW on 11/06/09 09:41am

I'm trying to pull together a budget for a long trip next year (9,000 miles) and want to calculate the cost differences btwn gas vs diesel class A.

I know there are significant differences with maintenance and repair costs. I've often read "better MPGs on diesel" but realized I actually have no idea how much better.

I am looking for something like this 2000 Winnebago Journey at PPL:

Any help with diesel MPG info is appreciated...

Thank you!


Full time from March 2010 to July 2011.
Solo trip to Africa in 2011
Single mom by choice April 2012
Looking to get BACK on the road with my baby boy

My YouTube Channel: Jennifer's YouTube Channel
My Blog:

Posted By: rvtommy on 11/06/09 09:56am

Most dsl. motor homes in that horse power burn about 6 gallons per hour!!! The V-10 Ford will burn about 8 to 9 gals. per hour. It would take alot of hours of driving to make up the diffrence in buying a dsl. motor home rather than a gas motor home. just my 2 cents rvtommy

this is rvtommy

Posted By: wallynm on 11/06/09 09:56am

Tell me how fast you want to drive and high much you plan to weigh and I give you a better estimate. It could be any where from 5.5 to 10.5. Over 80000 miles we get 8.3 and drive 55 to 58 and CGVW is around 31,000.

JWRVTexas wrote:

I'm trying to pull together a budget for a long trip next year (9,000 miles) and want to calculate the cost differences btwn gas vs diesel class A.

I know there are significant differences with maintenance and repair costs. I've often read "better MPGs on diesel" but realized I actually have no idea how much better.

I am looking for something like this 2000 Winnebago Journey at PPL:

Any help with diesel MPG info is appreciated...

Thank you!


Have a Diesel Engine Diesel RV Club

Have a Freightliner Yahoo Group or FCOC Web Page



Posted By: JenniferW on 11/06/09 10:01am

I forgot those important details.

I don't understand weight well enough, but as a solo RVer I don't think I would add more than is typical. I don't have a rig yet, so don't know what it would weigh...

I would also plan to tow my car, which is about 3,000.

I drive about 55 mph.



Posted By: spitfirepete on 11/06/09 10:05am

We got 8.9 MPG on our diesel on last summer's 9000 mile trip towing a Saturn Vue.....At 55 MPH we would have gotten probably around 9.2..Our rig weighs 32,000 fully loaded.

Peter and Linda
2011 Tiffin Phaeton
2007 Saturn Vue toad
Bichon and Cocker (spoiled puppies)

Posted By: djevans on 11/06/09 10:17am

The answers you get are going to be all over the place - "Generalizing," a diesel will get better mileage for a given load weight ALL other things equal - there "might" be even a bit more improvement if you tow. (the diesel being again better)

You're not generally buying a diesel RV for only mileage, but because they are better engines with heavy loads, generally MUCH quieter, more reliable, have PAC BRAKES, (or other compression brakes) most have Allison transmissions, (some gas units also have a smaller Allison) generally better on hills, bigger and better brakes, (air brakes that will seldom ever require changing in normal use) have better carrying and towing capacity, better driveability, and are just generally better built chassis'.

Diesels do have a bit more expensive oil changes, but overall, for us, our diesel is way ahead of our older class A gas unit.

But, if mileage is your only consideration, the diesel will never return enough to justify a diesel on that issue alone in most scenarios.

Don . . . near 36.171N 086.784W, TN near here
2003 Fleetwood Revolution 40C - HONDA Element
350hp Cummins ISC
2006 GL1800 HONDA GoldWing
- - - P i c t u r e s - - -

"HOPE" is not a strategy . . .

Posted By: JenniferW on 11/06/09 10:26am

Thank you all for the replies.

I had decided on the diesel because of the other benefits, but realized I knew nothing with regard to MPG.

The information given is very helpful to me.


Posted By: bojumill on 11/06/09 10:29am

our gas 34 ft Pace Arrow with chev 454 Carb. towing car over 9 mo we avg 6.2 MPG
a newer one with fuel in. would have done better
Bob & Judy

Bob & Judy Miller
Pam the Watch Cat
1986 Pace Arrow

1989 Jeep Cherokee 4 wheel drive & Blue Ox Tow Bar

Posted By: Mr.Mark on 11/06/09 10:39am

Jennifer, fuel mileage is all relative to weight and engine size. Our 425 hp diesel gets about 7.5 mpg on average driving about 58 mph. We weigh 40,000 lbs and pull a 3,400 lb toad.

I have gotten as high at 9.5 and as low as 4.5 (big hills).

There is certainly nothing wrong with a gas coach, every coach needs a loving family. [emoticon]

Safe camping,


2015 Prevost Liberty Coach, 45 ft, 500 hp Volvo w/1,750 lb. ft. of torque, 1.5 baths, 4 slides.
2017 Lincoln MKX AWD 335 hp twin turbo.

Posted By: BigSkyBob on 11/06/09 10:52am

I get 7.5 MPG driving 63 MPH. My toad weighs 6000 Lb. If I have a decent tail wind I've gotten 9 MPG and with a head wind and in a lot of mountains it drops to 5.5 to 6 MPG. I think 7.5 is a good average for a 350/400 HP DP with a toad and driven sensibly.

2008 Monaco Camelot 40PDQ, 4 slides, 2016 Dodge Ram 1500 Hemi Quadcab 4x4. Blue Ox, Garmin 760 LRM GPS, Doran Pressure pro on all 10, M&G Brake, 50 amp SurgeGuard, FMCA, Coachnet.

Posted By: djevans on 11/06/09 12:29pm

I meant to leave you our worst and best mileage
(ISC 8.3 -350HP)

- me driving very hard 6 to 6.5 (I generally also run the generator-same fuel source)
- me, average, most times we are "towing VUE" - 7.5 (possibly some light generator use)
- wife, at times (most times) 9 or slightly better (no generator) - she has hit 10 mpg (but that trip took forever!) [emoticon]

That should be close - the generator messes up mileage most times - if we are running the generator while driving, the coach chassis AC unit is on too

Posted By: MGO BLUE on 11/06/09 12:38pm

In february 07 I went to daytona in my 35 foot winnebago adventurer and spent $222.00 on gas took my new 43 foot tourmaster in july for $133.00 rode better and pulled 4500 pound toad with ease...I dont worry about mileage I worry about have to take the cost of the two fuels in consideration ..jim k

* This post was edited 11/06/09 12:53pm by MGO BLUE *

Posted By: mdock2 on 11/06/09 12:42pm

wit our 38' dp, we get about 9 mpg (between 8 and 10) did get 12 one time, but that was with a tail wind. i drive at 1750 rpms. (55 to 60)

Marty (KI4NAI)& Shirley
1998,38' DutchStar F/L Cat

Bits & Bytes,
Elks International (Webmaster)
PPA (Life Member)
National Park Travelers Club
Visited 158 National Parks
Places we've slept since 2007

Posted By: PJG061073 on 11/06/09 01:57pm

mdock2 wrote:

wit our 38' dp, we get about 9 mpg (between 8 and 10) did get 12 one time, but that was with a tail wind. i drive at 1750 rpms. (55 to 60)

HI, I am pretty much in the same range....(between 8 and 10) I have been taking 90-100 mile trips from home..

Have a wonderful day..
M&P .. ">
ANNIE - 2008 Safari Cheetah-40 SKQ- 08 Jeep Liberty Toad
CAT 7 350- C-7, Serial # WAX65944
ReadyBrake Surge Brake System integrated w/ReadyBrute Elite RV Tow Bar-BLUE OX Plate
Still in WPP..">

Posted By: TDInewguy on 11/06/09 04:32pm

Hi there! I have a very similar coach to the one you are looking at. There are a few things that you should watch out for. The one you posted only has a 4-speed transmission which is a negative, most have 6 speed transmissions, which helps in hill/mountian climbing and MPG.

That coach will probably get you 8.5-10MPG with that engine driving at 55-65MPH.

My coach has a 330HP CAT engine with a 6-speed transmission and pulling a 24' enclosed trailer that loaded weighs about 7000lbs I get 8-8.5MPG going 63-68MPH.

If I drive a lot faster say 70-75, then the MPG drops down into the mid 7 range.


2009 Newmar AllStar 4154
2014 VW Passat TDI - toad!
Featherlite 28' Enclosed car hauler
1966 GTO - super cool car as seen on Driven1

Posted By: teeznu on 11/06/09 05:09pm

2006 Winnie Vectra
Pulling a toad--8
Not pulling a toad--9
Keep the air filter clean.
60-62 mph


Posted By: Just Bob on 11/06/09 05:14pm

JWRVTexas wrote:

I'm trying to pull together a budget for a long trip next year (9,000 miles) and want to calculate the cost differences btwn gas vs diesel class A.

I know there are significant differences with maintenance and repair costs. I've often read "better MPGs on diesel" but realized I actually have no idea how much better.

I am looking for something like this 2000 Winnebago Journey at PPL:

Any help with diesel MPG info is appreciated...

Thank you!


The propane generator would be a deal breaker for me....that being said, if you're gonna go on a long trip like that, you DEFINATELY need a diesel coach.

Posted By: fcooper on 11/06/09 05:17pm

I agree with prevous post about the 4 speed transmission. Drove one of those when we were upgrading from gasser, and did not like the 4 speed. Also that coach you're looking at has the old style freightliner dash that is all one integrated piece. If you lose a guage on it, you can't just replace the guage, you have to replace the entire panel (much $$).

On my 2000 HR Endeavor 330 cat 6 speed allison towing 4400 lb toad I've averaged 8.45 mpg over 33,000 miles running about 64 to 65 mph. This also includes fuel used by the diesel genset, and it is running at least 70% of the time.

Good luck with your adventure.


Fred & Vicki
St. Augustine, Florida

Posted By: tatest on 11/06/09 05:48pm

Most of the time, choosing Gas vs. Diesel in a type A motorhome is not about choosing the power plant, it is about choosing the size of the motorhome.

Type A gassers range from under 14,000 pounds and 24-foot to 24,000 pounds about 38-foot. A gassers used to be available under 11,000 pounds, before slideouts made them heavier. Traditional A diesel pushers start at 26,000 pounds and 32-34 foot, go up to 40,000+ pounds, 45-foot.

More recently, front-engine diesel motorhomes have been produced that overlap more of the gasser range, i.e. small diesel motorhomes on the Sprinter chassis at 24-28 foot under 11,000 pounds, and larger front engine diesels 36-40 foot around 22,000-25,000 pounds. You will soon see more front engine diesel motorhomes, using smaller diesel engines not now used in motorhomes as one of the two currently used gas engines disappears from the market.

In the region of size overlap, the diesel can be expected to deliver at least 15-20% more mpg because diesel fuel is more dense by that much, and energy content is by the pound (though we buy by the gallon). You might see 25-30% better with the right driving style, because a right-sized diesel engine will be in a more efficient part of its operating range during cruise, compared to a one-size fits all gas engine that might be too big for a small motorhome and too small for a really big one.

The Journey you are looking at is in the size range where diesels overlap big gassers, and the diesels are much more efficient and pleasant to drive. I would not buy a gasser that big. If that's the size you want, you should be looking at diesels.

What you can't expect, is a 45-foot, 40,000 pound diesel motorhome to get signifcantly better mileage than a 14,000 pound, 26 foot gasser.

Tom Test
Itasca Spirit 29B

Posted By: sowego on 11/06/09 06:33pm

MPG for any coach varies depending on miles on engine, condition of coach, weight onboard, terrain you'll be driving in, driver habits, speed, winds, tire pressure and more...Most broken in diesel engines of the age you wrote (a 2000) may average about 8 to 10 mpg if the whole coach is in great shape. But it could be as low as 5 to 6 mpg.

You just won't know until you take the coach out on a very long drive where you can try to get an average over many different conditions, speeds, etc. Until you have it loaded with your belongings, water, fuel, etc. you'll not know what the exact milage will be. Try to find out what mpg the previous owner got. If you are new to this coach or motorhomes it will take a little while to "learn this coach". You will learn how to manage the coach for the best mpg.

I'd budget for the lower mpg then you'll not be underbid and be pleasantly surprised if you do better.

* This post was edited 11/06/09 06:44pm by sowego *

2002 Tiffin Phaeton
2005 Malibu Maxx toad

Posted By: RayChez on 11/06/09 06:41pm

I have had both, a 36' gasoline with a V-10 Ford engine that would get 8-9 mpg and now I have a Caterpillar 3126-E and it gets about the same as the gasoline mpg. But diesel is cheaper then regular gasoline at the moment. It could change.

2002 Gulf Stream Scenic Cruiser
330 HP Caterpillar 3126-E
3000 Allison Transmission
Neway Freightliner chassis
2017 Buick Envision

Posted By: Horknee on 11/07/09 08:38am

One real important thing you should keep in mind is "most people lie about mileage" and a lot just don't know the truth because they don't calculate it properly or they can't.MH on different angle,foaming etc.Forget about mileage or buy a smart car and camp in that.

Posted By: the trippers on 11/07/09 08:56am

33 ft '06 Southwind, 8.1 liter gas, Allison 5 speed, towing a Jeep Grand Cherokee LTD - 4,400 lbs, in mountainous Utah/Arizona, about 7 mpg, using odometer and gallons purchsed, some generator use, conservative speeds, seldom over 62 mph.

2011 Jayco Greyhawk 31DS

Posted By: ljr869 on 11/07/09 10:41am

RVs and budgets don't mix well.

2009 Fleetwood Bounder 35H
Ford V-10 w/ Banks

Posted By: steveownby on 11/07/09 01:30pm

Hi Jennifer,

It so happens that I have a very good friend with an '01 Journey 32' with the same Cummins ISB and 5 sp Allison transmission that is in the motor home you linked to. He gets 10-12 mpg regularly. He drives 60-65 on interstates. The ISB is widely known to be the most fuel efficient diesel being used in motorhomes. The 5 sp trans is a compromise and you would be better off from a useable power standpoint to have a 6 sp but I would not consider this to be a deal breaker. You will be slow up hill while towing but you will get to the top. Winnie builds a quality, well engineered motorhome. If you make an offer on this Journey, make sure to include a complete service on the engine, transmission and chassis.

Let us know what you do & how it turns out.

Good luck & safe travels,
Steve O

Steve Ownby
2003 Monaco Signature

Full-time since 2007

Posted By: StanleyandIris on 11/07/09 02:17pm

42' DP, 330 Cummins, no toad, under 60 MPH and we average 8-9 mpg. I think you can use this for a ballpark figure in planning your budget and be safe.

I really like that unit. Congratulations on the selection.

Have fun.


Posted By: travis0793@sbcglobal on 11/07/09 02:48pm

I drive back to South Dakota from Northern Cal every year and I average 10 to 11 mpg on our 03 Fleetwood Expedition 300 Cummins diesel. The kicker is to not drive over 60 to 65 miles per hour and I buy the PRI diesel additive and put it in everytime I fill up. I do agree with the others that fuel for your coach is the least expensive aspect of owning a Motor Home, you have to look at the entire package.

* This post was edited 11/08/09 11:03am by travis0793@sbcglobal *

Posted By: Starburst2 on 11/07/09 07:52pm

It's nice to know what to expect in the way of miles per gallon but in my opinion fuel is the cheapest part of motorhoming and I would not put too much stock in the few mpg you may achieve one way or the other. The big expenses are depreciation and financing. It's better to just enjoy the motorhoming experience and ignore the few dollars difference you will spend on fuel whether its diesel of gasoline. JMHO

Posted By: thunderstruckhd on 11/07/09 08:00pm

Figure 7 to 8 MPG. About $3500 to $4000 in fuel over 9000 miles at todays fuel prices...

Prevost H3-45 Featherlite Vantare
500HP Series 60 Detroit Diesel
Assorted trailers,toys and toads
And Zoie the Doberman.(01/26/01 - 07/23/11) R.I.P.

Posted By: JenniferW on 11/08/09 01:47pm

Thank you all SO much!

I can't believe I am actually starting to understand some of this stuff.

(Though usually with the help of my new Automotive Technology textbook.)

; )



Posted By: Deen on 11/08/09 02:20pm

I've seen everything from 3.3 mpg on the flat fighting a headwind at 70 mph to 254 mpg going down a grade with the throttle off. On the flat, towing our Ody on a dolly it usually runs 12-13 mpg, but average is just over 8.

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