I bought a used 2017 ToyTaco Sport AC MT about a month ago . First Toyota of any kind. I've a basic understanding of how octane is used in engines that require it. Manual says to use 87 or higher. After trying 89 I am convinced the engine runs a bit better. This is my third tank of the 89 . While I will continue using the 89 I wonder if anyone else has experienced the same?. Is this a matter of 87 is good enough but 89 is best, perhaps 91 is even better?.. or have I somehow fooled myself ?.