folks, the minimum for this car is 91! octane booster is not recommended for this engine either. the engine is controlled by a computer and it has different program "maps" to tune the engine to the type of petrol used. in warmer/hotter climates you better use higher octane or you will for sure get knock which can harm a lot of components and cause premature engine wear.
stick to using a good branded petrol (Chevron then shell or if you want a discounted petrol, quicktrip) of 91+ and you should be good to go.
i wish you cats could find some 100 octane. I mean, i just lightly press the pedal and the Q will move like a raped ape. smooth idle, sweet exhaust smell. really good stuff.