reg or mid

[natethegreat38]

Originally Posted by mark2908

After reading several conflicting threads, I did a 3 tank test this fall.
I have a 6 mile commute each way, with lot's of hills and frequent starts and stops.

On 87 octane with Ethanol, my last three tanks were:
40.44 mpg
38.72 mpg
39.17 mpg

On 89 octane with Ethanol my 3 test tanks were:
37.41 mpg
36.76 mpg
36.65 mpg

The next three 87 tanks came back up slightly, all above 38 mpg.
For my commute, I got better mileage using 87 octane. Also, I noticed longer crank times, with 89 on colder mornings, and higher GPH numbers at idle across the board.
No earth shattering conclusions here, but it does confirm Bailout's claim that if you drive for FE your mileage will go down with higher octane.

nice little study! Thanks for the info- it's short and sweet (and informative enough). Thanks for sharing