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Owners manuals usually make a generic comment like minimum of 91.
The octane rating refers to the ability to resist ignition under compression. Ethanol fuels have an Ron (relative octane number)
The ecu with help of the knock sensors will determine the ignition timing. If you put 91 in your tank the ecu will be forced to advance the spark to prevent knocking, however this reduced efficiency. Whereas if you run a higher octane fuel the ecu can ignite it closer to tdc increasing the engines efficiency. (ignition timing is also adjusted for other factors such as emissions but that's not as much related to the fuel you use)
While ethanol is very good ay resisting ignition under compression, ethanol has a much lower energy density than octane.
My VE likes fuel.
If you've got a V6, then dont cry. It could be worse.
I get 13.5 or something like that around town per 100km and i use 98 octane.
Can get to canberra-sydney-canberra on one tank on the freeways.
My mower and whipper snipper cant run on e10 lol...
This is the fuel consumption in my v6.. not being a economical driver either lol. Just got plugs changed and its already going down on fuel
Edit: Blue dotted line is fuel consumption.. seemed to go up when I got the exhaust.. I just like the sound of it