Heisenberg wrote:
Without a tuner running higher octane fuel is a waste of money. The "computer" is programmed to run whatever octane your owners manual prescribes. Unless you have a tuner it will not properly adjust for the higher octane. I am an Instrument Technician.
That is only true for a non-high compression engine where higher octane fuel is not recommended by the manufacturer. Generally, for today's engines that are higher compression engines, the ECU will retard timing when using a lower octane fuel which will result in less power and usually higher fuel consumption.
Some reading for you:
http://www.economist.com/blogs/babbage/2012/09/octane-ratingsOh yeah, I'm a banana