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Old 05-14-2014, 09:11 AM   #1
Artemus Gordon
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How do you calculate MPG?

I often see people reporting "fantastic MPG" figures on their Tow Vehicles. Many state "I got 22/25 MPG on my trip"! Or others report, I averaged 14.5 on my trip.

My question is simple, how did they arrive at that number? I for example use "true average", not a "static reading" from computer. While my truck gets great numbers going down the highway, the average drops significantly when I am navigating in traffic or cruising streets. If I say it gets 14 MPG, that's miles divided into fuel used. Not a reading during one aspect of my driving! In fact, I was informed by an engineer, that a "true number" should be based on using 3 tanks of fuel and actual miles covered! Is that not the only important number? If your truck carries 30 Gal, it's hard to believe it has a range of nearly 700 miles? If it does, who needs a Tesla? Any thoughts.?
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Old 05-14-2014, 09:30 AM   #2
Phil P
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Hi

I use the total mileage for one leg of a trip.

The following was not a pleasure trip. We generally only travel 250 to 300 miles a day when traveling for pleasure. This trip was an emergency to relocate the Montana.

I drove straight thru from Florida to West Virginia divided the total gallons in to the total miles and got 17.5 MPG not towing.

The next day hooked up to the 5th wheel and drove from West Virginia to Ormond Beach Florida, got 6 hours sleep and continued home the next morning.

I divided the total gallons in to the total miles and got 12.5 MPG towing.

When we are traveling for pleasure I use a spread sheet and put the miles and gallons at each fuel stop in the spread sheet and it gives me the MPG quickly. It will change a lot from one stop to the next but the average for each leg is what you are interested in.

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Old 05-14-2014, 09:33 AM   #3
Bigboomer
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We use the true average from the truck's computer and also monitor fuel usage and miles driven to compare and confirm. I can tell you that when not towing I will average 14-16 MPG plus, when towing 10-12 MPG on the highways and 8-10 in the hills and mountains. We can carry up to 100 gal onboard (2 - 50 gal tanks with auto switch over) so we can run a bit and be choosey on fuel if necessary.

Example: last trip to Sioux Falls and back from the East Coast we averaged 11 MPG for the whole trip. This includes driving around in SD while there so we put on a total of 3,100 miles and used a little over 280 gallons of fuel. Don't need to tell you that it is painful to fuel up....
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Old 05-14-2014, 09:33 AM   #4
bncinwv
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My methodology is even simpler. I fill the truck tank, I fill the overflow tank, and when it disappears to the extent that there is about a quarter to a half tank in the truck tank, then I repeat the process. Never have calculated anything, probably would not want to know since hopefully we can afford to keep purchasing the fuel to repeat the process. If it ever gets to the point where we can't do that, MPG isn't going to matter anyway. Sorry, I don't guess that was much help!
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Old 05-14-2014, 10:03 AM   #5
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In all my years RVing, I have never exceeded 12 mpg. Have always divided miles driven by gallons consumed. Now , over all mileage on my truck is about 14.5. When running road speed without load, it reaches 19.5 on occasion. So, I'd say 11 towing and 18 touring.
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Old 05-14-2014, 10:31 AM   #6
Irlpguy
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I created an Excel spreadsheet quite a few years ago, I enter each fill up when we are traveling recording Fuel Cost, Gal used, and Miles traveled, I have set mine up to calculate each fill up and average each amount. My calculations also convert US MPG to Canadian MPG since we are filling up with US gal and like to know in terms we are used to.

At the end of our annual 1800 mile trips to Arizona we know exactly what our fuel has cost, what our MPG was on each fill up and and leg of the journey as well as the average for all of the above. Excel will do about anything you want and once set up will do it automatically.

Included in our Excel sheet is our camping cost, our electricity as well as other repair and maintenance costs associated with the trip.

It is my opinion this is the only accurate way to obtain MPG as the on board computers are averaging all the time, it will give you a average if you zero it out at each fill up but that is not what I want to know and is not as accurate.

I do not think "fantastic" is a word that can be used in the same sentence with MPG, especially when towing the big Montana's.

For some of us Bingo the cost of fuel and the amount we spend on fuel is very important and does enter into our travel plans, since we have found that this cost will equal almost half of our total trip cost. Guess my pension just is not up to snuff....

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Old 05-14-2014, 10:36 AM   #7
bethandkevin
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I generally reset the trip odometer and gallons used and let the truck figure it out. When on the road I'd rather think about what I'll do when I get there, or what I'll cook over the fire when I get there. Math is for work!
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Old 05-14-2014, 11:15 AM   #8
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I use phone app "Gas Record Plus", tracks total MPG Avg, and last tank. Keeps records of every fill up, GPS location, and price I paid. You get directions map location if you want.

My over all, Avg MPG is 11.4. Normally see around 10 MPG pulling, and 14.5 MPG empty. Got better MPG on Low Sulfur Diesel, but since Ultra Low Sulfur became the law of the land, MPG drop 3 MPG.

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Old 05-14-2014, 11:26 AM   #9
richfaa
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We also do not calculate MPG. The Lie O meter gives us a ball park figure. I know we get about 10/11 towing and 15/16 Solo. If the numbers decrease greatly from those benchmarks I know something may be wrong.

We do not keep spread sheets although it is not a bad idea. We know pretty much what we have to spend and as long as we have about 1.98 left over at the end of the month we are good. Fuel is a huge expense for those of us that travel a lot. Now we do use Quicken that has all those fancy spreadsheet and bar graphs and we categorize all expenses. We do look at Quicken at least twice a year to see how it goes and If I do not clutch my throat we keep on going.

Bingo we are going to have to reevaluate how we do things..
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Old 05-14-2014, 11:34 AM   #10
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I know a guy that gets 17.5 pulling a 4200 pound camper with a 5.3 Chevy. Trouble is my nephew owned the truck before he did and got less than 10. The last time I went out west a guy in a 2012 Cummings ask what mileage I got "O bout 10. I ask what are you getting "O bout 10" I think if someone is getting 12 they drive a lot slower than I do.
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Old 05-14-2014, 11:41 AM   #11
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On my previous truck ('07 F350) I found the truck computer to be about 0.5 mpg better than calculations using odometer and pump gallons readings. That is pretty close so I quit bothering with odometer and pump readings.

Have not done the calculations on the new truck yet to verify the computer. Everyday combined hwy/city driving the computer shows about 15.5. On a long straight relatively flat no wind 70 mph 2 1/2 hour non stop interstate drive a couple months ago the computer showed 22.7. Although I was running a consistent 70 mph I was also consciously trying to keep the instant mpg graph at the highest I could at that speed. Pulling the Monte last summer showed 10.5 with high winds most of the way. Haven't had a lot of opportunity to check towing numbers. Happy with that if calculations verify it.
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Old 05-14-2014, 12:11 PM   #12
jswharton
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I calculate mine based on miles and gallons. During 2012 & 2013 I averaged 14.2 & 14.2. This year my best tank was 16.9 and my worst was 9.8. That's 10-11 towing and 14-16 not. So much depends on the % of highway miles. Another major factor is speed. The difference between 60 & 65 is about 1/2 mpg so it adds up. At 60 the rims are about 1600 - 1700 and seems to be the sweet spot. The actual usually only differ by a tenth or so from the truck computer.

The amazing thing to me is when comparing to my previous 2001 f350 with the 7.3 and 410 rear end. Towing was virtually the same and non towing is better with the newer ford.
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Old 05-16-2014, 12:17 PM   #13
bncinwv
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Quote:
quote:Originally posted by Irlpguy



For some of us Bingo the cost of fuel and the amount we spend on fuel is very important and does enter into our travel plans, since we have found that this cost will equal almost half of our total trip cost. Guess my pension just is not up to snuff....

Didn't meant to place anyone in a category, Ed, and at some point in time, MPG and range will be a factor for me as well. My pension plan does not exist at present, since I am still five days a week for 48 weeks a year. The other four weeks are our travel time, and as long as we have the means to travel, we will travel, that was the underlying gist of what I was saying. I do estimate fuel budget costs at a conservative 10 MPG, and prefer to leave it that way, since then what we have budgeted for fuel for our trips always has a cushion.

Bingo
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Old 05-16-2014, 02:44 PM   #14
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Also, one more observation, when the percentage of "Bio" diesel goes up the milage goes down, for example 10% in the diesel will cause milage to drop by more than 10%. This little feature comes with the benefit of higher food costs for us all.
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Old 05-16-2014, 03:09 PM   #15
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Got to agree on the cost of diesel. Once we got the solar added the cost to move the rig has surpassed anything else in the expense category. I am aware, of course, that what we spent on the solar should probably be figured into that equation, but we didn't do the solar only to save on camping costs.
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Old 05-16-2014, 04:00 PM   #16
richfaa
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Our round trip to Florida for our winter stay cost us over 900.00 in diesel. I could look back in Quicken and know exactly what our diesel cost for the year was but I won't. It is figured into our travel and Rv budget and we can handle it.

we know what we have coming in,we know what our fixed expenses are we know what is left. That is our budget. We worked long and hard and saved for these years and we will enjoy it.. That is what we mean by if we have 1.98 left at the end of the month we are good.
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Old 05-16-2014, 05:23 PM   #17
JandC
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I just use the lie-o-meter on the truck more to keep track of how everything is doing. I keep my speed down, accelerate slowly, and try to anticipate my stops to conserve fuel, but the bottom line is we need to go from point A to B and we have to pay for it.
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Old 05-17-2014, 02:39 AM   #18
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I used an android gas app to track my diesel usage. But now with 300 gallon capacity, I fill up in the late Winter and that usually takes care of it until late Summer when prices are usually the lowest. Use a diesel additive and may add more to the tanks if prices fall or if we go on a long trip. Our truck computer tracks the MPG and I average around 9 MPG for an average year. Longer trips equals higher MPH. Shorter trips equals lower MPH. We bobtail the truck a lot while at home and camping which explains the 9 MPG. Would probably average 10.5 MPG if eliminated City driving, but that is no fun....

Set the cruise control at 5 MPH under the speed limit. When going down hills, truck will go 5 MPH faster than the cruise control speed. Then, the 3-stage Jake brakes will not allow the truck to exceed 5 MPH over the cruise speed. When at the bottom of a hill, the truck will resume to the set cruise control speed. I rarely use my brakes on the highway.
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Old 05-18-2014, 08:45 PM   #19
Artemus Gordon
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I also like to know or at least estimate how much a trip will cost. I always us 11 MPH for my budgets and diesel cost here in Redding. We are usually the highest place in the Nation. Paid $4.29 at Chevron this morning!
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Old 05-24-2014, 06:41 AM   #20
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Quote:
quote:Originally posted by Irlpguy

I created an Excel spreadsheet quite a few years ago, I enter each fill up when we are traveling recording Fuel Cost, Gal used, and Miles traveled, I have set mine up to calculate each fill up and average each amount. My calculations also convert US MPG to Canadian MPG since we are filling up with US gal and like to know in terms we are used to.
Ditto, again.

I've kept track of all of my vehicles this was since 2006. It is the most accurate method of computation. And yes, I travel with a laptop so I record this information whenever I fuel up.

Since I purchased my 2012 Ford F-250 Superduty crew cab short bed 4x4, I've averaged 12.40 mpg (as of 5/20/2014), this is almost all towing, but also included those times I'm Monte-free, about 7% of the time.
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