Gasoline Experiment, Part 5

Okay.  One month of gasoline testing is completed.  Here are some comparative numbers:

May  = $173.65 total spent, 1561.7 miles traveled, 44.842 gallons used, 34.83 MPG
April = $173.58 total spent, 1489.9 miles traveled, 44.729 gallons used, 33.31 MPG

At first glance, one can see the total spent and the gallons used were almost identical.  That means the average price I paid was very similar for both months ($3.87 in May and $3.88 in April).  However, in May I got 71.8 additional miles and, therefore, 1.52 more miles per gallon.  Had I purchased all my gas at the generic grocery store, I would have bought an additional 2.156 gallons and paid an additional $8.36.

While my experiment did not result in less money out of pocket, it did result in a savings of gallons I did not have to buy.  I also realize there are other variables which were not limited that could have had an impact on my results.  After all, my per-tank MPG ranged from 32 up to 39.  Looking over my old numbers, though, my generic gas MPG ranged from 27 to 35 with monthly averages ranging from 30 to 32.

I am satisfied that buying the more expensive gasoline at Shell is definitely providing me with increased MPG resulting in a small savings over buying the generic grocery store gasoline, and I will continue to believe this until my gas milage drops below 33.