I did not realize the Focus was 12:1. I now accept that it probably will benefit from 93 octane fuel, especially considering that the owner's manual says that it will.
So now I just want to know how much it benefits, so I can see if it is worth using.
If 93 fuel costs 15% more, and I gain less than 15% increase in MPG, then it is not worth it for fuel economy.
Now if it gains HP, then that is another matter, as I can justify it by acceleration gains rather than on economy gains.
Top gear tested what - a Mustang? How much HP gain and what was the HP? We can then scale it to the Focus HP and come up with a guesstimate.