Calculations for Gas mileage (spreadsheet included)

[ches111]

I created the spreadsheet below so I could decide how long it would take to repay my cost on the predator purchase. I was assuming about a 1 - 1.5 MPG advantage using the Predator. But I was not sure what that would equate to and how long it would take to pay it off in gas savings.

I then expanded it into a tool for me to use to decide which tune I wanted to run based upon Higher Octane costs. Again if I saw an improvement in mileage using higher octane "what does it gain me and how much will it cost".

Since everyone talks about how hot the 93 tune is, is it worth it if I stay the same on mileage? How much would it cost me per year extra if mileage did not change but performance did?

So I expanded the spreadsheet to allow me to calculate those costs.

There are a few constants used such as the size of your tank, the cost of your fuel at your favorite station for the grades you might use. I also included E-85 as an option since I see that question asked alot as well. You should also put in your Approximated number of miles driven per year.. This can all be found in the lower left of the spreadsheet

I decided the best way to calculate this is by defining my average cost per mile. The ACPM*Number of miles driven per year would give you an annual cost of participation in your favorite grade of fuel.

If you were to find out that you are getting 1 MPG BETTER using 93 Octane vs 87 Octane is it worth it? Now you can see..

I set up the spreadsheet from 10 - 25 MPG averages in .5MPG increments.

You can obviously modify to your actuals and still do the calcs.

Hope this helps someone.

If there are any proposed changes please let me know.. Also please let me know if you find any errors.

This is an Excel Spreadsheet..

[06MonteSS]

wow, nice job man... just downloaded it and ran my numbers through it... cool stuff...

I use 93 octane which is about 3.79/gal around here in CT now... so with my 17 gallon tank and about 21,000 miles a year, my cost per mile is $0.185 and the cost per year is $3,882.439.

[ches111]

Here is how I am going to use this tool.

Run a tank or two of 87 and get my actual MPG with that tank. For me right now it is 15.9MPG
Run a Tank of 89 and get actuals.
Run a tank of 91 and get actuals.
Run a tank of 93 (if I can find a station with 93) and get actuals.

I am going to use the 87 Octane numbers as the baseline.

From there I can use the spreadsheet to extrapolate what my approximated fuel cost per year would be.

If I get better fuel economy and better performance from 91 and the cost shows that its cost per mile is in line with 87 then I might use 91. If I find I am within $50.00 per year in savings just to run 87 vs 91 then I still might use 91.

All numbers are approximated since we do not know what the cost of fuel will be later this year. But it should give you somewhat of a ratio since they ALL tend to go up by the same amount.

[ches111]

I think I will revise it to allow you to use your actuals like a 15.x something as a first constant and go up and down from that number in a .5 mpg increment.

Think that would help?

[06MonteSS]

sure, why not...

it worked ok for me though, since my average has been 20.5... hehe....

[ches111]

K here is an update.. On sheet two or the Actuals Sheet there is an option to enter your actual MPGs as a constant as well.

It then calculates the loss or increase in MPGs as a positve or negative .5 mpg increments.

Update is in the op..

[ches111]

Did another update and no need to go to the second sheet now.

If you do nothing it will leave the median value of 16.0 MPG and calculate from there.

However if you now enter your Actual MPGs it will auto calc in increments and decrements of .5MPG

Should be cleaner.

[ches111]

No love here?

No feedback?

Not useful?

Who Cares?

[jcbst12]

Either way, city or highway I show a loss of around $80 for the year.

Lets say a 1 mpg increase across the board:

87 octane tune
City: 16 Highway: 19

93 octane tune
City: 17 Highway: 20

Where I live, this comes to be a difference of $66.70 and $86. That won't kill me.

[jcbst12]

Nice job ches111! Thanks for the input!

Next question.....to remove TQM or not to remove TQM?

Oh and how many of you guys run the 93 tune? Worth it? I just filled up with 93 and retuned the truck with the 93 tune on my lunch break. (I kept the TQM "On" for now) What can I expect?

[06MonteSS]

I'm afraid to run this again since my Mobil 93 gas is now $4.27 here.. hahaha

[jcbst12]

Yeah that hurts

[ches111]

Jcb,

Since you now have the 93 tune installed you might want to look at turning off the first two TQM parameters and leaving the third alone. If you have TQM parms to play with that is.

Hint Hint Hint

That was for both of us Lew

[06MonteSS]

hahahaa... thanks Ches!!!

I play with mine in private though..

HAHAHAHAHAAA!!!

[Grumpy_Aero_Guy]

this is cool....

for me, running 93, it's an extra $16/month. Well worth it....IMHO