OK I did some math to try and see "where" buying higher octane gas would pay off financially, if indeed it pays off in higher MPG.

It boils down to this: with the difference in the octanes being 16 cents per gallon, it would be cheaper per mile to buy the higher octane ONLY IF the higher octane consistently provided AT LEAST 5 more miles per gallon per tank than the lower octane.

I'll keep everyone posted on the results of the higher octane tank.