The manual also states that running premium will result in increase performance.
Most engines are tuned with high and low ignition tables. Which if is true for the Focus it would make sense why they recommend regular but also state that premium will increase performance(Page 354 "Octane recommendations" last sentence in the owners manual.). One day I'll hook it up to my Dash Hawk and try and figure it out.
My G8's had high and low octane tables and running on the low octane table the car made around 8HP less than the high octane table (Stock). It switched to the low octane table when it detected a predetermined knock count withing a set time frame. It was kind of a PITA when trying to tune the thing because it was pretty sensitive and switch over when it wasn't needed. I ended up just cloning the high table on to the low since I wasn't planning on running anything less than 94.
God I miss that car.
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