2021 Mountain Aire, Average 7.2 MPG

[Yellville]

Originally Posted by tankcj

I was just going to mention this. Very valid point. Also any Aqua Hot/oasis use will have an affect (small). I wonder how many are hand calculating their mileage versus taking the numbers from the dash readout.

I assume the mpg numbers on the dash are calculated using the actual fuel burned by the engine and not by just using the tank sending unit. We know the dash shows the instant mpg which means it has the ability to measure actual fuel consumption by the engine, not depletion of the tank.

I can tell you that when my trip meter says I used 49 gallons since I reset it at fill-up, I end up putting in more fuel than that which I assume is generator consumption since we run the generator constantly here in the west in the summer.

I'll look closer at gallons added at fill-up vs gallons used on the computer next time I fuel. I don't believe that fuel depletion from the tank has any direct relationship to the mpg reported by the computer. If this were the case then you could run the generator with the engine off and watch the mpg go down over time as you sit, which I don't think happens but haven't thought to check until now.

[LeslieGary]

For our 2018 Dutch Star 4362 towing a Jeep Grand Cherokee the dashboard shows an average of 7.4 MPG.

We don’t use the generator very often and typically use AC for hot water, so I believe they have had a negligible impact on our fuel consumption.

[tankcj]

Originally Posted by Yellville

I assume the mpg numbers on the dash are calculated using the actual fuel burned by the engine and not by just using the tank sending unit. We know the dash shows the instant mpg which means it has the ability to measure actual fuel consumption by the engine, not depletion of the tank.

I can tell you that when my trip meter says I used 49 gallons since I reset it at fill-up, I end up putting in more fuel than that which I assume is generator consumption since we run the generator constantly here in the west in the summer.

I'll look closer at gallons added at fill-up vs gallons used on the computer next time I fuel. I don't believe that fuel depletion from the tank has any direct relationship to the mpg reported by the computer. If this were the case then you could run the generator with the engine off and watch the mpg go down over time as you sit, which I don't think happens but haven't thought to check until now.

My Silverleaf used to be pretty accurate when comparing to hand calculations but at some point my ECM was updated and now my dash MPG is way off but my hand calculations are still about the same. Of course the hand calculations have to be done without using the generator or Aqua Hot to get an accurate calculation. My point being that (in my case anyway) the software could be inaccurate.

[Fiesta48]

The Freighliner LBCU is not accurate. It reads 6-9% high. Sorry to disappoint you all but 7 mpg is really 6.6. The one with 5.8 is really 5.5.
Accurate MPG is total miles and total gallons over several fillups. Generator usage, headwinds, hills, short trips and any speed over 55 reduces MPG and all must be included.

[Yellville]

Originally Posted by Fiesta48

The Freighliner LBCU is not accurate. It reads 6-9% high. Sorry to disappoint you all but 7 mpg is really 6.6. The one with 5.8 is really 5.5.
Accurate MPG is total miles and total gallons over several fillups. Generator usage, headwinds, hills, short trips and any speed over 55 reduces MPG and all must be included.

I don't have the Freightliner.

I wouldn't consider the generator or water heater as part of the mpg. These things have their own consumption rates that should be measured independently. If I wanted to know the energy consumption of my home air conditioner I wouldn't include the toaster just because it used it at the same time.

Of course if you are trying to estimate your total fuel cost for a trip it would make sense to try and add in all these things. I only care about mpg to know the efficiency of the engine. I don't really care about the total fuel consumption and if I got 4 mpg or 8 mpg it wouldn't change my driving behavior in any way.

[sramer]

Originally Posted by Fiesta48

The Freighliner LBCU is not accurate. It reads 6-9% high. Sorry to disappoint you all but 7 mpg is really 6.6. The one with 5.8 is really 5.5.
Accurate MPG is total miles and total gallons over several fillups. Generator usage, headwinds, hills, short trips and any speed over 55 reduces MPG and all must be included.

I calculate mine the ole fashion way, miles divided by gallons, but I will tell you. My trip computer is dead on.

[Yellville]

Originally Posted by sramer

I calculate mine the ole fashion way, miles divided by gallons, but I will tell you. My trip computer is dead on.

That certainly works if you don't run the generator. Unfortunately it is too hot right now to run without the rooftop ACs. I'll give that a try this winter, which is a long way off. For us it goes Summer, January, Summer.

[Mmdg02]

7.2 mpg is great, I am getting 6.2 mpg with our 2019 Mountain Aire, towing a Jeep Grand Cherokee, average speed 70 mph on the interstate and with the generator running most of the time.

[Ann n Gene]

I get about 7.2 with my 8.9L New Aire towing an F150 King Ranch. My loaded coach weighs 38200 and the pickup is close to 6000 so I am happy driving 64 mph living the dream. I really posted to thank you guys, the is the very FIRST fuel mileage post I have seen on this forum where everyone who posted appears to be reasonable, accurate and yes, believable, and I have been on this forum since it started! Well done gentlemen!

[danleininger]

Well apparently I’m pretty heavily loaded. With our Expedition (5000#) attached we go across the scales at 55,000#. I guess my DW and I need to start a diet.

Our MA in on a Spartan Chassis.

We track our fuel economy both ways using the Dash figure and mathematics. Our lifetime average per the Dash is 6.5. Our Calculated numbers vary due to generator and Oasis usage. However, on days when the Gen or Oasis haven’t been a factor the Dash MPG is usually pretty close. Other factors that affect MPG is the angle of the MH while filling. If I’m nose up I seem to fill fuller than if I’m nose down.

Great topic!

[tom chelbana]

With our 18 LA with K-3 605 averaging 7.1 is a surprise to have that much power and still get that millage for 51k coach and 6k tow.
Newmar Man

[Rev. Roy]

Originally Posted by Yellville

I don't have the Freightliner.

I wouldn't consider the generator or water heater as part of the mpg. These things have their own consumption rates that should be measured independently. If I wanted to know the energy consumption of my home air conditioner I wouldn't include the toaster just because it used it at the same time.

Of course if you are trying to estimate your total fuel cost for a trip it would make sense to try and add in all these things. I only care about mpg to know the efficiency of the engine. I don't really care about the total fuel consumption and if I got 4 mpg or 8 mpg it wouldn't change my driving behavior in any way.

How can you measure them separately? They come from the same tank and are running together while driving. I subtract 1/2 gal from my total amount of fuel needed for every hour I use the generator. That includes use when sitting. That's the only way to come up with a reasonably accurate MPG. I have a 12.5KW generator.

[zzotte]

I can’t help to just laugh when I read some people’s post they spend a 1/2 million bucks on a coach that weighs north of 45k lbs and worry about gas mileage hahaha keep them coming

Zzotte

[danleininger]

Originally Posted by zzotte

I can’t help to just laugh when I read some people’s post they spend a 1/2 million bucks on a coach that weighs north of 45k lbs and worry about gas mileage hahaha keep them coming

Zzotte

I don’t think we are worried, just interested and comparing what others are experiencing.