Can New Sumitomo Tires Cut Fuel Mileage??....& UPDATE - Human Error!

[Tom Cherry]

37 minutes ago, Larry Laursen said:

Fuel milage variation is very real from full tank to tank.  This because the tank runs across the width of the coach.  A one-to-two-inch difference in the left to right side of the coach while fueling will give about 5 gallons difference.  If you are only filing about 30 gallons this is significant.  I have tracked my fuel usage for 140,000 miles and the tank-to-tank fill varies from 5 to 12 mpg.  The 10-fill average is 7.5 to 8.5 mpg.  Total lifelong is average is 7.8. 

OK….OFF THE DEEP END. I have an Excel spreadsheet.  I actually have a column set up that does the 10 fillup moving average.  It is, for those of us a little anal, to evaluate fuel conditioners.  I have a cum for life column as well.

IF, from a statistical standpoint, one wanted a very precise number, then one would write a formula for a weighted average 10 fillup calculation.  In that the average would be calculated each fillup based on the gallons pumped….

YES….Some folks play video games, cards, Sudoko, what ever to keep their mental acuity….some play around with electronics and figure out how to fix “seemingly UNFIXABLE” PCB.  EXCEL challenges me…

[jimc99999]

21 hours ago, Tom Cherry said:

OK….OFF THE DEEP END. I have an Excel spreadsheet.  I actually have a column set up that does the 10 fillup moving average.  It is, for those of us a little anal, to evaluate fuel conditioners.  

Interesting. I don’t do the weighted average, just mpg for each tank and on the total gallons and miles driven. But, I also enter generator hours, so I guess when I’m bored someday I could set up not only a “last 10” average but factor in generator usage. 
 

Although as a programmer, while I dabble in Excel out of curiosity occasionally, I’d be more likely to write a program to do more complicated calculations. And thinking about this…I might have to think about writing an app anyway now because my current process is to take pictures of the odometer, fuel pump, and generator hours gauge, and enter the values in a spreadsheet later. But detecting numbers in a picture is supposed to be relatively trivial now, so just taking the pictures could potentially create the entire entry for me. 

[Martinvz]

Jim, a little VB Script works and it is easy. Even I can do it 😎

[Larry Laursen]

I have been using an Excel spreadsheet for my mileage since 2000 on my 2000 and 2005 Endeavor.  I fill anywhere from 20 to 60 gallons on trips and run a fair amount in mountains.  Also upped the tire diameter some so the trip is off some.

This is what mine looks like. Tank, 5 tank, trailing 10 of 5 tank and overall.  The functions are easy to use in Excel.

 

[Dennis N - 2005 Windsor]

Two comments - 1) measure the height of your fuel tank and divide the volume by height to find the "gallons per inch" - it might surprise; it seems like my Windsor was close to 10 gallons per inch when you consider the fuel neck height. 2) if someone opened your fuel tank and help themselves to some of your fuel, it would show up as a very low MPG with your calculations.

[Ivan K]

3 hours ago, Larry Laursen said:

I have been using an Excel spreadsheet for my mileage since 2000 on my 2000 and 2005 Endeavor.  I fill anywhere from 20 to 60 gallons on trips and run a fair amount in mountains.  Also upped the tire diameter some so the trip is off some.

This is what mine looks like. Tank, 5 tank, trailing 10 of 5 tank and overall.  The functions are easy to use in Excel.

 

Do I read it right that your new muffler dropped MPG? Can't tell when it was installed. 

[dl_racing427]

10 hours ago, Larry Laursen said:

I have been using an Excel spreadsheet for my mileage since 2000 on my 2000 and 2005 Endeavor.  I fill anywhere from 20 to 60 gallons on trips and run a fair amount in mountains.  Also upped the tire diameter some so the trip is off some.

This is what mine looks like. Tank, 5 tank, trailing 10 of 5 tank and overall.  The functions are easy to use in Excel.

 

That really illustrates just how much individual fills can vary, while overall mileage stays quite consistent.
The variation from less than 5 to over 12mpg is pretty eye opening.