P400 petrol

[Rexb]

Has anyone experienced much of a difference between unleaded 91, 95, and 98?

[DazzaTD5]

wrong part of the forum...

but to answer your question...

Octane rating wont increase any power from a petrol vehicle.
Octane rating is a fuels resistance to compression...

Octane rating - Wikipedia

[Tins]

Changing the octane rating will alter how the various sensors respond though. Altering timing etc. My old Mk 5 Golf would get better economy, but you would need a slide rule to calculate it. My Barra Ford doesn't care, it drinks like a sailor ashore for the first time in months. No point giving it top shelf.