This topic has been beaten to death.. If you enjoy driving in a less than sedate manner you will enjoy paying the difference in price for premium fuel.. You will actually get better fuel mileage when driving in heavy stop and go traffic where you frequently are on the throttle accelerating or over hilly terrain.. It would be a waste of money for someone that doesn't drive in a spirited manner or is driving mostly on the highway on flat terrain at a speed under 80 MPH.. There are knock sensors that cut back on the ignition advance when needed to because of low octane fuel use, heavy load or driving up a hill.. The use of high octane fuel allows the timing to advance more and will advance even more when octane booster is added to the fuel.. A 50/50 mix of water and methanol and using 93 octane fuel has the same effect as you get using 106 octane gasoline but you more than likely wouldn't feel a difference in power unless you had numerous modifications and a tune using a Hondata FlashPro..