Real Fuel Economy of the Monaco Vesta

Unbelievable claims for fuel economy or MPG for RVs, including the Monaco Vesta, are being tossed around by dealers, blogs, online videos, and a host of other sources.  Products claiming wild results on How to Get Better Fuel Economy or MPG in your Motorhome.  We’ve tracked our fuel economy in the Vesta for the past year and there is more to it than just seeing what your on-board computer has to say.  RV Manufacturers love to toss around MPG numbers but these numbers aren’t backed by ANY research or track testing, so the only way to get accurate information is to track the MPG yourself.

How to calculate the Miles Per Gallon of your RV or Motorhome:

First off it’s come to my attention that many people don’t understand the proper way to track fuel economy of a Motorhome.  We’ve had people tell us they receive 15 MPG in their 40,000 pound 42’ diesel pusher…I mean come on….there is no way you’re achieving over 10 MPG in a 40’ foot RV (most are lucky to get 7 MPG).  Here’s the 5 main rules to accurately track the fuel economy in your RV:

  1. DO NOT believe your on-board CPU, it’s lying to you.
  2. Write down the current mileage immediately on your receipt.
  3. Keep detailed track of your generator usage, and write it on the receipt (# of hours and power draw).
  4. Keep track of your driving habits (i.e. we always drive at 55 mph on highways).
  5. Note your terrain and/or route.
mpg receipts

mpg receipts

The Formula for obtaining your MPG is simple, just save up a few receipts with the info from above and follow this formula:
Miles ÷ Gallons = MPG
Example: 1000 ÷ 100 = 10 MPG

The Bad News about RV Fuel Economy:  Unfortunately there is no way to track your MPG 100% accurately in an RV.  With altering terrain, temperature, wind, weather, altitude, weight fluctuation, generator use, and a vast number of other variables it’s impossibly to get an exact reading.  The only way to accurately test fuel economy is to load down the RV and take it to a controlled track for testing.  So next time you read about a new RV getting 15 Miles Per Gallon take it worth a grain of salt until you personally track the numbers.

If you’re interested in seeing how I’ve documented the fuel economy, or MPG, in our 2011 Monaco Vesta Motor Home read below.  If you need any help tracking your numbers, or if you have a Fuel Economy story to share please do so in the comments section all the way at the bottom.


12/2013 Final MPG Test for Windy

I thought for our last trip with Windy the RV we should bring our MPG back to the real world. No more averaging the Smart MPG, just real numbers…ok so they’re not exactly ‘real’ because this trek documents our trip from the mile high city of Denver, CO to Louisville, KY; you’ve guessed it downhill all the way! Why not let Windy go out with a bang?
2011 Monaco Vesta MPG
1206 miles driven
108.265 gallons consumed
11.14 MPG average
$401.24 total fuel cost
Thanks for the great memories Windy, we really enjoyed seeing our beautiful country with you.

08/2013 Update 23.85 MPG Average

With this RV Miles Per Gallon update I decided to take my last MPG claim of 22.9 and quantify it in a more realistic way. So as soon as we crossed into Washington I filled up the RV. I logged all miles driven in the Smart and the RV while in WA, and before driving into Canada we filled both vehicles up to complete the Miles Per Gallon test for Washington. So the crazy dream of our motorhome getting 23 MPG may not be 100% accurate, at least we were able to average 23.85 MPG while traveling all over the mountainous state of Washington.

The route we drove the RV across Washington

The route we drove the RV across Washington

1211 miles driven in WA
116.552 gallons consumed
10.4 MPG Average
$468.88 total cost to explore WA in RV

1326 miles driven in WA
35.591 gallons consumed
37.3 MPG Average
$140.65 total cost to explore WA in Smart

Average MPG for WA: 23.85 MPG
Total Cost to Explore WA: $609.53 (and worth every penny)

Fuel receipts for travel in RV and Smart Car in Washington State

Fuel receipts for travel in RV and Smart Car in Washington State

Again I must point out our onboard CPU that calculates MPG on your RV is just an estimate of fuel used and Avg. MPG. Don’t trust it, it will lie to you. We used more Gallons of fuel and got way less MPG then the computer would have us believe…dang liars! 🙂

Fuel Economy of Monaco Vesta in WA

Fuel Economy of Monaco Vesta in WA

I love seeing the difference between the Smart Car and the Monaco Vesta…but I love combining the MPG even more 🙂 There is one hole in my math (you know I can’t be perfect), I forgot to fill up the Smart Car when we crossed the border into WA! So scientifically this entire test was compromised…good thing it’s not a real science project or I would have gotten an “F”. Haha.

06/2013 Update 22.9 MPG Average

Yes we are now averaging 22.9 MPG! You read it correctly! My math skills aren’t the best but you’ll be happy to know I double checked these numbers 🙂
Windy the RV MPG Through Mountains, Deserts, Forests, Oceans and Cities…we’ve seen it all over the past few months.
See the snapshot of our route via our Smart RV gps tracking device…yes we’ve seen a lot!
Start Location: Lake Havasu City, Arizona Date: 01/11/2013 Odometer 23,087 miles
End Location: Bend, Oregon Date: 06/17/2013 Odometer: 26,262 miles
gallons used: 331.604
miles driven: 3175
RV MPG Average: 9.6
cash spent: $1377.06
Since our RV has been in service for several weeks I decided to track the MPG of our little smart car as we drove all over the Pacific Northwest. Over the years of traveling I never took into account the MPG of the Smart when totaling our RV MPG. One day it hit me: The RV has 25,000 miles and the Smart has 25,000 miles! Why haven’t I ever looked at the Smart PLUS the RV and averaged for our TOTAL MPG on the Road? DUH? So what is the verdict:Smart Car (our Toad) MPG
Start Location: Eugene, Oregon Date: 06/25/2013 Odometer 23,442 miles
End Location: Eugene, Oregon Date: 07/25/2013 Odometer: 25,398 miles
Through most of Oregon and some of Washington we drove the Smart (Eugene, Portland, Eugene, Florence, Eugene, Mt. Hood, Portland, Seattle, Portland, Eugene). Yes we went to Eugene a lot because that’s where the Monaco Factory Service center is located, not a bad town to be stuck in!
gallons used: 54.017
miles driven: 1,956
Tow Car MPG Average: 36.2
cash spent: $239.95

Now keep in mind this MPG was with the Smart trunk completely loaded down with a makeshift roof rack on top that, I’m positive, destroyed the aerodynamics of this little car. Sure these were mostly highway miles however we traversed over mountain ranges, through winding ocean side paths and all over national forest roads. I think it’s safe to say my original MPG number of 37.777 is still on target for more normal circumstances.
So take this 36.2 MPG average for the Smart Car and add it to the 9.6 MPG average of the RV and I feel happy to report our new and improved Miles Per Gallon on this portion of our road trip is:
22.9 MPG

If this doesn’t convince you to purchase a tow car for your RV then I don’t know what will. Either way this new MPG math has got me excited to hit the road and keep drivin! If you’re trackin’ your MPG give us a shout in the comments below, can you beat our numbers, or are you towing a hummer behind your 40 footer? Would love to hear from you cause nothing sparks a conversation like MPG.

11/2012 Update to Monaco Vesta Fuel Economy MPG

After the last ridiculously unbelievable MPG reading I figured I should switch it up a little. I’ve thrown consistency to the wind and added a crap-load of variables, but I figure since I’m not getting paid to make these fuel economy posts I can do whatever the heck I want. So here’s the scoop for this edition of my Monaco Vesta Miles per Gallon:
• Our Horsepower was bumped up from 260 to 300
• I’m driving at 62 MPH (instead of 55)
• Economy Mode onOur route takes us from Dallas, TX to Cloudcroft, NM, past Phoenix, and eventually into Lake Havasu City Arizona. Desert, hills, mountains, hot, cold, rain, you name it and we saw it on this trip. We ran the Generator a few times since we’re living off the cord, we had the dash A/C on for the majority of the trip, and we ran the heater a few hours as well. Other things are standard: towing the smart car, ½ full on our freshwater, using the oil and fuel supplement, etc. Without further ado….the numbers:

12 mpg rv

12 mpg rv

Odometer Start: 22,086
Odometer End: 23,083
Miles Driven: 997
Gallons Used: 94.07
MPG: 10.6
Generator Use: 3 Hours (1.5 gallons)10.77 MPG – Grand Total for fuel economy of this trip in the Monaco Vesta
***As you can see the on board computer was off as usual, this is exactly why you can’t trust the numbers your RV gives you!
Altitude of visited cities in feet
Snyder, TX: 2,320 Cloudcroft, NM: 8,600 Alamogordo, NM: 4,336 Eloy, AZ: 1,513 Lake Havasu City, AZ: 735

texas to arizona map

texas to arizona map

So what does this mean? I have no idea, other than the MPG’s during our travels across the USA varied greatly. It’s safe to say if you’re buying an RV that claims a specific MPG you can pretty much throw that to the wind. Varying terrain, different loads, temperature changes, altitude changes, humid air, dry air… all adds up to one giant “?”.

If you’re curious to learn more about Fuel Economy Numbers in the Vesta read some of our other posts, it’s extremely interesting (at least for me since I’m payin’ the bills).

If you have any wild ideas of how to save fuel let us know in the comments below. With as much travel as we’re planning to do over the next couple years even 1 MPG savings will help.

10/2012 Update to Monaco Vesta Fuel Economy MPG

Unbelievable! That’s what I feel about the recent Miles per Gallon test on our Monaco Vesta. So unbelievable I’ve checked 3 times, confirmed my credit card charges, verified the miles on Google maps, and even confirmed the altitude of each city we filled up in.

The past 2 days have rushed us from St. Louis Missouri to Dallas, TX. We’ve kept up our standard style of driving (cruise set to 55 mph, economy mode on, towing the Smart car, etc) but our reading is literally unbelievable. It may have to do with cooler weather, not running the A/C, not using the Generator at all, or maybe even the oil and fuel additive we’re testing. There are a few hills along the way, but for the most part this trip was pretty boring and flat. As you can tell, I’m still not sold on these numbers, but here you go anyway:

Odometer Start: 21,138 (with additive)
Odometer End: 21,679 (with additive)
Miles Driven: 541
Gallons Used: 37.06
MPG: 14.6
Generator use: 0
Altitude of fill-ups in feet
Valley Park, MO: 421 McAlester, OK: 735 Denison, TX: 728

st louis to dallas map

st louis to dallas map

Have you ever averaged 14 Miles per Gallon in your RV (or anywhere close)? Think you know how I got to this unbelievable number (‘cause I can’t figure it out)? Share your thoughts in the comments below, and yes we read every comment. Read some of our other posts if you want more details on the MPG of the Monaco Vesta.

08/2012 Update to Monaco Vesta Fuel Economy MPG

I’m happy to report this month an increase in MPG of Windy our RV. Maybe it’s the fact she just turned 20k, maybe it’s the oil and diesel additives, or maybe she just loves the hills of the northeast. No matter what her deal is I’m excited to say our fuel economy is tracking along this month (and last month as well) higher than when we started this year!
This month we drove from Maine down to the Jersey Shore, and across to Philadelphia, Pittsburgh, Cleveland, and finally Wakarusa, Indiana for a service appointment at the Monaco factory. If you’re not familiar with this drive during the summer months here’s the skinny: Hot, Humid, Rain, Wind, mountains, hills, and everything in between! We took a beating in Pennsylvania and had to run the generator to power both A/C units (32 amps) due to the nearly 100 degree temps and 80% humidity. We also hit over 20 tolls which caused us to accelerate and decelerate more often than normal. We drove the Vesta through 5 or 6 cities and were stuck in bumper to bumper traffic for about 2 hours total over the month.
We also added a second bottle of the oil supplement (on the first fill-up in this month) to the engine since we didn’t have the appropriate amount at the time of the oil change. I drove the entire month with the economy mode on, I’ve noticed a difference in the shift patterns allowing me to enter 6th gear earlier, and keeping the transmission from downshifting 3 gears when climbing a small hill in cruise. After living with these shift patterns it seems the economy mode should continue to help conserve a tiny bit of diesel while travelling down the road. All other driving styles are the same as the original posts (tow car, 55 mph, etc).
Here’s the details on the Fuel Economy Numbers:RV Start with Additive 19,349 miles New Hampshire 07/14/2012
RV end with Additive 20,669 Indiana 08/05/2012
1320 miles driven
119.165 gallons used
11.08 mpg
– 5.5 hours generator use at high draw (3.5 gallons)
Fuel economy for the Monaco Vesta 32 foot PBS = 11.41 Miles Per Gallon

08/2012 Update to Smart ForTwo Fuel Economy

For those of you who are curious here is the scoop on the Smart Car Fuel Economy:
amish farmlands
start: 04/15/2012 – 12,736 miles
end: 07/30/2012 – 15,376 miles
2640 miles
63.14 gallons
Smart Car Miles Per Gallon: 41.81 MPG

07/2012 Update to Monaco Vesta Fuel Economy MPG

06/04/2012 Today we received an Oil Change (odometer reading 17,803) that was paid for by a company who has designed a new fuel and oil supplement to increase fuel economy on both diesel and gas engines. (FYI – the 2011 Monaco Vesta uses 25 Quarts of oil, and a typical oil change with filter costs around $300). With the engine warm the oil additive was put in the engine.
At fill up I am required to add 1 oz. of fuel supplement for each 10 gallons of diesel. I am keeping track of the MPG we receive in our Monaco Vesta in order to provide the company with real-life fuel economy numbers. Once I thoroughly test the product I’ll let you know if it works, and how you can purchase it.
Our current trek takes us from PA, through the Finger Lakes of NY, into Canada via Buffalo, and down to NH via East of Montreal. The roads are hilly, and we’ve hit some traffic in the cities of Canada, and at both border crossings. Despite these changes in driving there is still an increase in fuel economy of approximately 1 MPG, looks promising right? I have activated the “economy” mode on the transmission and plan to leave it on during the remaining posts about fuel economy. Here are the most recent fuel economy numbers I’ve tracked on our 2011 Vesta:
RV Start with Additive 17,856 miles Pennsylvania 06/04/2012
RV end with Additive 18,876 New Hampshire 06/26/2012
1020 miles driven
89 gallons used
11.46 mpg
– 1 hour generator (.5 gallons)
Fuel economy for the Monaco Vesta 32 foot PBS = 11.52 Miles Per Gallon

July Monaco MPG Route

July Monaco MPG Route

06/2012 Update to Monaco Vesta Fuel Economy MPG

We’re entering the hills and small mountains that make up North Carolina and Pennsylvania. We also hit a little bit of traffic outside of Washington, but nothing that slowed us down to a crawl. Expected my MPG to worsen a bit, but it seems the 10.5 might just be the average MPG for the Monaco Vesta. I have decided to keep the “economy” mode off during this trip, I didn’t feel it made much of a difference in our fuel economy.
RV Start 16534 miles South Carolina 04/14/2012
RV End 17856 miles Pennsylvania 06/04/2012
1322 miles driven
123 gallons used
10.71 mpg
-2 hours generator (1 gallon)
Fuel economy for the Monaco Vesta 32 foot PBS = 10.8 Miles Per Gallon

South Carolina to Pennsylvania Driving Route

South Carolina to Pennsylvania Driving Route

05/2012 First Fuel Economy Post for 2012

Today I’m a little unhappy to report the Fuel Economy of our 2011 Monaco Vesta 32 foot RV. We began 2012 in Dallas, TX and we’re now in Myrtle Beach, SC. Our route took us south from Dallas into Nacogdoches, then across to New Orleans, and on to the gulf shores of AL. We turned northeast into Savannah, and further up the coast to our current location of Myrtle Beach. As you can guess these roads were mainly flat with little elevation changes. We have also met little head winds, mild temperatures and mostly smooth roads.
We’ve continued our normal driving style
• 55 MPH using cruise control
• Towing the Smart Car (1,800 lbs)
• Minimal In-Town RV driving
• Average Weight of coach 25,000 lbs (3,000 lbs less than the max GVWR)
We have used the generator for 4 hours at a medium-high load for an estimated 2 gallons total use.
For 2012 Monaco released a recall on the transmission to adjust the shifting and add the “economy” mode into the computer. This gave me hope that better fuel economy was on the horizon for our 2012 travels. I drove each mile in 2012 with the Economy Mode ON. As you can see from the photo our trip computer was excited about the new economy mode too……a little too excited.
Last year I chalked up our average Miles Per Gallon to the ever changing terrain of the west, and the new engine (We averaged 11.2 MPG last year). Now I’m faced with an engine that’s broken in with over 15,000 miles and flat smooth roads. Combine that with our conservative driving style and I’m not sure what to tell you, so I’ll let the numbers do the talking.
03-07-2012 through 04-14-2012
1608 miles
155.318 gallons
-2 gallons for Generator Use
Fuel economy for the Monaco Vesta 32 foot PBS = 10.489 miles per gallon

Texas to South Carolina RV Route

Texas to South Carolina RV Route

Now don’t get me wrong, I’ll take the 10-11 MPG achieved by the Monaco Vesta over the typical class A Motorhome average of 6-8 MPG. With the smaller size, front engine diesel, and aerodynamic features of the Vesta I was hoping for something closer to 12-14 mpg. Oh well, stay tuned; as long as we’re traveling in our Windy I’ll make sure to continue posting about the Fuel Economy for the Monaco Vesta. *****As of this post Monaco still has not released any official fuel economy numbers for the Vesta, so anything you read from other websites are simply speculation.*****

05/2012 Smart Car ForTwo Convertible Fuel Economy

For those of you who are curious I also ran the fuel economy for our 2009 Smart ForTwo Brabus Convertible, gotta love these numbers!
03-07-2012 through 04-14-2012
1450 miles
37.777 gallons
Fuel Economy for the Smart Car = 38.39 miles per gallon

Want more info?  Check out our previous articles on Fuel Economy for the Monaco Vesta

If you have a MPG story about your RV please leave a comment below.

Famous for my "how-not-to" videos, and typically the man behind the camera, sometimes I’m forced to be here in the “spotlight”. When you see my face you’re probably reading something more technical than adventurous, but either way I do my best to tell it like it is and infuse my opinions into the commentary…after all this is a blog and not MSN.

Comments (59)

  • Eric Birmingham

    Jason. Next week I am picking up a 2011 Monaco Vesta from a nice fella in Maryland. It’s gonna be REAL cold. I’m driving my barely broken in Vesta (18K miles since new) down south to Atlanta. Have you ever used Diesel fuel additives when you had Wendy, or did you drive all temperatures and terrains without fuel additives? Thanks, Eric from Italy

  • Michael

    Sorry, I think you all have it wrong. I was at a gas station in Tombsone AZ filling p the “pickle’ 77 GMC. A lady pulls in in a Prius, inquires as to our antique and asks about mpg. I say well, 9 to 10. She says she gets like 46. I say oh. Do you have a on board shower, toilet sink, frig, oven, microwave, generator, solar electric and screened windows. Well no, she replies. I ask how much her Prius weights. She takes a guess. I whip out the phone and the calculator and do the math for mpg per lbs. Then I do the same for our 15,500 lbs, including Mini towed. Turns out I run down the road slightly better then a Prius.

  • Jason and Patti

    Bottom line, which class A RV gets better mileage, a gas one or a diesel one????

    • Diesel.

  • Andrew Williams

    Can just keep apples with apples..I just found your blog wanting to know the average mpg for miles driven..not what your generator used. Has some tested their diesel drive train or not. Some clarity please!

  • Rod

    Hi Jason. Do you have any thoughts to share about your experience with your Avanti front engine diesel?

    • We did not have a good experience with that coach or the engine. We gave it back to the manufacture and got the monaco vesta which was soo much better for us.

  • John

    I do have a ? Do all diesel’s use DEF and is it hard to find on the road.

    • Dan

      I’m a mechanic, not an RV’er, so I’ve got a different background than most here. Diesels after chassis model year 2010 use DEF, other than some Navistar engines. DEF is not hard to find on the road, it’s at major truck stops in bulk (fuel pump type hose), larger auto parts stores (usually 1 to 5 gallon jugs), truck dealers (overpriced jugs), farm supply stores (jugs), and other outlets. Not hard to find, just sometimes hard to find the best price.
      Another note, even though it is water based, do not spill it on your clothes. The smell will hang with you for a long time.

  • David Camden

    If you change your air filter to a K&N filter! For the air filter for the engine. It will give better gas mileage. Also using synthetic mobile 1 oil. Makes the engine quitter less ware on it also better gas mileage. Doing these two things will give you around 2 more miles to the gallon. 🙂

    Ps.. Lucas gas treatment on every fill up..

    Do the changes on at a time so you can see how well it’s working for you!

  • steve

    I have noticed my 2013 NewMar Ventana motorhome with 360HP Cummings ISC engine I was getting between 6 to 8 MPG. I had a friend that is a truck driver tell me things he conserve diesel leading to better MPG.1 if driving in the city Coasting into the stoplight most of the time when you get to it the light would turn green.2 if your driving threw rush hour traffic instead doing the same speed as then lets say there doing 35MPH I would do 30 so I’m not always on and off the gas.3 if so hot you have to run your AC it a good idea to find a place to park at a truck stop or a rest area with some shade tell it get cooler outside every one know if your AC is on the engine has to work harder and the more fuel you use with doing all of thing I have see some change in are MPG to 8 to 10.5

  • Jacques L.

    Hi Jason.
    We’ve been fulltiming for 3 years and I’ve been a long-time lurker on your website. I was catching up tonight after a… er… slight pause *blush* in my lurking, and read through your post on fuel economy for the Vesta. When we first started fulltiming I came across the attached brochure, which I’ve emailed to you for your reading pleasure, should you so desire. If nothing else you should at least peek at page 17. I think it gives an excellent breakdown of the factors affecting fuel economy for RVs :>)
    Full disclosure, I drive a 2006 Safari Cheetah and it has the Caterpillar C7 350HP engine… but the principles in the brochure apply to all motorhomes, IMHO. Although by your standards our motorhome is a behemoth at 41 feet (+ towing our Subaru Forester), I agree 100% with your rant about the fuel cost complaints by RVers. You choose the lifestyle, you put on your big boys pants and pay for the fuel or you go for sticks and bricks and pay for home heat…it’s all about lifestyle choices… Well said!
    Keep up the great posting!

  • David L Densmore

    REALLY enjoyed these articles, and your attention to detail.

    I question your advice about filling up in the morning when the fuel will be colder. If the fuel was stored above ground, there would be a large fluctuation in the temperature of the fuel. But fuel is stored under ground, making the temperature much more stable, and I would find it hard to believe that there would be any statistically different temperature between morning and evening.

    Good advice on file economy from trip computers. We had a 1998 dodge van that was right on the money, I know because I keep records of my gas usage. But the rest of the vehicles we’ve had have been optimistic liars.

    Another factor often not considered in measuring accurate fuel mileage, is the accuracy of the speedometer. Especially with a change of tires, many vehicles speedometer is not accurate. For instance our 2000 Class A gas, is about 5% high. When the speedometer read 60 mile-per-hour, I’m actually doing about 55. What this means is that the odometer is affected, and the true gas mileage is affected. When figuring the gas mileage I have to deduct 5% to get the actual gas mileage. So if I divide the miles by the gallons, and get eight MPG, then I need multiply by 5% and my actual mileage is 7.6 mpg.

    Another factor is that comparing gasoline and diesel fuel mileage figures is somewhat like apples and oranges. Several methods can be used to help equalize this, one is to add 10% to the gas mileage of a gasoline vehicle to make up the difference in cost between diesel fuel and gasfield, and also to consider the higher cost of maintenance and repairs on the diesel vehicle. For instance your $300 oil change would be $50 on our gas vehicle. $250 buys a lot of fuel over the life of an oil change interval.

    Thanks again perplexing article that really got me to thinking. It’s also good to see that I’m not the only one to try to stick to 55MPH on the interstates.

      • Richard Ineson

        I employ something I call (Oildialysis) It is a combination of different technologies that synergistic ally work together. I learned this of 15years of trucking and use it presently with my 2001 Dodge dually Deisel. Great results E me if inerested

  • Jason’s recent math (06/2013) is fun but of course, a fantasy.

    Actually – It is Dollars per Mile that really counts.

    So – by making your mega trips now when you are 30-something and fuel is not yet $10/gallon, you are really saving money!

    Keep on Truckin!

  • I use the Fuel Log app on my Android phone to track my RV mpg. On a recent 12526 mile road trip over various terrains driving from New York to North Carolina to Illinois to Arkansas, Texas, New Mexico, Arizona, California, Oregon, Washington, Idaho, Wyoming, Colorado, Nebraska, Iowa, Illinois & North Carolina again, then back to New York, I tracked our fuel usage using this app.

    Driving a 1994 Fleetwood Tioga Montara 29 ft Class C RV with a 7.5L V8 gas motor and towing a 2005 Jeep Liberty we averaged 7.53 mpg. Our best mpg was 9.44 (must have been on a downhill grade with the wind behind us) and our worst was 5.82 mpg driving thru the mountains.

    The Free App was simple to use. After fueling up I just put in the mileage, the total gallons of fuel and the price per gallon and it calculated all the stats.

  • Jeffrey

    Your revised mileage estimate to include the Smart car is hilarious. I can’t believe someone took it seriously in your comments. But I think you’re really going about it all the wrong way. You should make the Smart start pulling it’s weight…. or maybe pushing it’s weight. I wonder what your MPG on the Vesta would come it if, say, you were close to pulling on the highway for a long trip, then, start the smart, drop it in drive with a brick on the gas pedal. Then once you’re on the hwy put the Vesta in neutral. 🙂 Sure, this could result the both the Vesta and Smart needing new bumpers, and maybe a new transmission or two for the Smart, but you should really explore all your options since , as you know, MPG is EVERYTHING!


      • Jeffrey

        Jason, you could also reroute the vapors off your new composting toilet to the Smart to increase it’s gas mileage. Seriously…..thereby running it off the chili you all consumed several nights prior. Maybe rename the Smart “Chili” or “Chili Tug”……LOL

        I hope you know this idea(as well as the other) was a complete joke. 🙂

  • Rick

    Hi JASON –

    Sorry – you cannot compute fuel economy this way – you are literally comparing apples & oranges, or in this case – combining an RV and Smart Car.

    1> Mathematically you cannot Average 2 separate Averages to realize a 3rd Average. That’s like saying that if you have an average life span of 75, and your spouse’s average life span is 91, that the average life span for each of you is 83! (Good for you – not so much for her) I have heard that happy spouses each live longer, but you see why this makes no sense. Your average life span will always be yours, and hers wiill always be hers.

    2> What you can do is compute a total Miles Traveled mpg. To do this you add mileage for both against total fuel usage. Doing it this way =

    miles gals
    RV 3175 331.604
    SC 1956 54.017
    Total 5131 385.621 = 13.305 mpg.

    So what this is saying is – – in driving 2 vehicles you traveled a total of 5131 miles, using 385.621 gals of fuel to do so. So your total Travel mpg = 13.305mpg.

    This makes more sense, and shows again why you would want to tow a small economy vehicle to use when you don’t want to/ need to use the big boy.

    3> But – Windy still only got You cannot really compare or combine the Smart Car to the Vesta for fuel economy, or much else. They are 2 different beasts. Other than being self-powered transportation machines they otherwise totally different in size, weight, carrying capacity, function, etc.. So – you have to stick with your original, independent analysis, where you calculate the mpg for each as a separate vehicle based on the mileage each achieved in their own right.

    5> Use of a Toad is a good idea – especially traveling as you guys do – where you tend to park for at least a week in one location. Then you can use your dinghy for local travel using far less fuel. Makes sense to me!

    However – it was a fun read, and interesting to see your take on this topic Jason. Nice try!

    Travel Safe . . .

  • Randy

    We live in ours so the 40”, 31,000l lb, 4 slide Monaco Diplomat is the way to go. I’ve kept track of every mile and gallon of diesel that we’ve used for 19,607.1 miles. Bob is right, don’t trust one fill up. My best is 15.98 mpg but the next is 4.25. My average overall is 7.56 mpg. Find your optimum torque and run in your final gear as much as possible. Use cruise control. I drive around 62 mph. Faster is worse mpg and slower is slightly better. If you travel in Texas during August you will run the generator and all the roof AC units, which will reduce your mpg.:)

  • This is a very wise post! Brilliant tracking there for your MPG. I live in a smaller converted RV, so my MPG is quite good. I’ve also assembled some of the best ways to save gas and money.

  • Bob

    you should never trust the mpg on one fill up. unlevel when filling, foam accumulating in diesel will introduce errors. You need to average several fill ups to get a better reading.

    I get 9.5 mpg from my isb engine 36 ft class A in Florida and 8.9 – 9.0 gallons on a 10,000 mile loop out west (I do not want to know the mpg just in the Rockies 🙂 I drive 62 mph or 5 mph below the speed limit if I have to go slower and stay in economy mode when ever feasible.

    Increasing speed increases wind drag and it would be a velocity squared relation ship so 55 mph would be more fuel efficient if you can tolerate it and if you do not think it is less safe (people speeding by you at 80 mph)

  • Mike Taylor

    I too own the 09′ Brabus Conv., what a great vehicle! The car gets more looks with the 17″ wheels than cars costing many times more! I bought it for use as a toad, but haven’t pulled it yet. Friends have fancy golf carts that cost what I paid for my Brabus with only 6,000mi, ($12,500) I tell them, you may think it’s a joke of an automobile??? I choose to look at it as the Worlds Finest Golf Cart with AC and Air Bags 🙂

    • ha ha, i like your thinking mike!

  • John T.

    If i put some cool racing stripes on my RV I think it gets better fuel economy. Stickers rock! It’s like shaving your body makes you run faster….

  • Roger Nelson

    I read your fuel mileage post’s andhad on question, on the highway, what is the speed you Maintain? Have you tried a tank of fuel 5mph faster or slower? I really do appreciate your real world fuel economy numbers as many people whopost do not rack accurately. Our class A 1998 winnebago 32′ gas brave has achieved 9 mpg when traveling at constant 50/52mph, 6.5mpg at 70mph and 7.5 to 8mpg at 63/65mph (seams to be my sweet spot)

  • Mike

    May I suggest you get a ScanGauge II for your fuel efficiency? It attaches to your OBD-II port. The OBD-II port is required by US law on all vehicles 1996 and older.

    I have one and I’m a better driver for using it.

  • Randy

    This is why I got the MB Sprinter based RV, but I don’t have the room to lounge nor the ccc of the Vesta, nor the price. I can load up on 55 gallons of water, 57 lbs of propane, that drives the genny too and dry camp for LONG periods of time but w/o the larger storage I have to come out of the wild to do laundry and even to get different season clothes. But since I mostly use it for getaways and am no snow bird it has plenty of space for us and the dogs and still fits in average parking lots so I don’t need a toad, though I hang a motorcycle or bicycle off the back, and this is getting 18+ MPG.

    I would love to see how you guys pack the Monaco, it looks great when you clean it up, but where does all the stuff go, I don’t see you wearing the same clothes, so you must have a laundry system, you must have a work setup where things are left out, but when the cameras are rolling you look like you just commuted there from home, not camping.

    Do you still have the snow boarding gear and wet suits with you?

  • Mahdey

    The maxxforce 7 has a great aftermarket to boost fuel mileage and power. 2000rpm for that engine is the sweet spot for mileage. Before I sold my truck with the 6.4, I deleted the dpf (which i know you want do to “stay green”), injectors, reflashed computer and injectors. I went from 8 mpg to 21.4 avg mpg. If you think about it, all the fuel you are saving is offsetting the cost of having to drill all that extra oil you are wasting, offsetting the impact of a dpf delete. Best of luck..oh, even with the dpf delete, my truck was cleaner than your average midsize v6 sedan according to Ohio e check.

    • Mike Taylor

      Mahdey I agree 2,000 rpm is the sweet spot for this engine. In general running a diesel just a hair above max TQ is best, as one slight inclines the engine will pull at max TQ. I reflashed my 09′ 6.4 King Ranch F-450 with 19.5 wheels and 4.30 rear and I only went from 10mpg to 12.5 after the doc delete…Runs like there’s two 6.4’s under the hood but not much more mpg. I would never ever sell my truck if I could get 21mpg! That means the Vesta would achieve about 16-17mpg!

  • paul van

    I guess you went down more hills then up in the west.

  • When we were at the Pomona show and the RV salesman told us it would get 12-14 mph we just looked at each other and giggled. Salesmen! Gotta love them.

    • When we first purchased our Vesta Monaco was hoping for 14-17 MPG…needless to say they were a little upset when we returned with our first fuel economy test around 11MPG…..ooops. ha.

  • Jeff Hyslop

    Consider that maximum fuel economy is achieved when you are at the lowest speed that will hold top gear. That means your best speed maybe higher than 55.
    My Diplomat is best at about 62. I have to get up to 65 to get into 6th thenr back off to about 62. Another help is the Silver Leaf VMS-pc engine monitoring program

  • Mark G.

    I noticed on our ’08 Dynasty w/425 hp Cummins that our mpg increased after 25,000 miles. We are at 52,000 miles now. We weigh 40,039 lbs. plus we are pulling our 3,400 lb. toad (Honda CR-V). The Aladdin computer says that we are averaging 8.2 mpg over 52,000 miles. I check the mpg at every stop. It ranges from 6.0-9.0 ….. but to me, seems to be 7.5 mpg mostly.



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