On the inside of my filler cap (UK spec) it states use EN228 RON95. I intend to experiment with RON98 next month to see if it makes a difference to 1) Performance and 2) Economy. I need to justify the extra 7p per litre for the extra 3RON.

Nice to know that the UK and US specs for fuel are different. You would think that it was possible to have one rating across the world for international fuel and car companies.