My car is E63 2007 model. N52 engine RON91-98. I have been using RON95 for 3years now. No issues, engine working fine! As fuel price is down decided to give RON99 a try. Filled up Shell Vracing and gave it a run. To my surprise there is no difference. This fuel being RON99, expected an appreciable diff in accleration from RON95! Could the knock sensor be faulty and not making the necessary ignition reschedule?