Regarding use of High Octane fuel in AQUA & PRIUS; I have on numerous occasions explained that this is not required however every second person is mixing high octane to his liking getting no benefit but only increasing the running cost. Well here is quote from Prius Chat;
Higher octane=more resistant to detonation/preignition
more resistant to detonation due to having slower flame front propagation
slower flame front propagation actually = potentially less power (oddly enough), unless the car is designed for higher octanes (ie..higher compression, timing, etc)
Will it hurt anything to use a higher octane than recommended by manufacturer? Only your wallet in most circumstances,