93/91 octane, you are WASTING your money. I just had this conversation with my wife for the 100th time
There is no benefit, all you're doing is collecting tons of carbon buildup and decreasing your fuel efficiency and power due to your engine requiring more fuel to perform at the same level it would if you just put 87 in it. Your engine is unable to burn higher octane fuel efficiently because of lower compression ratios. You can put 87 in a vehicle that requires premium because most/if not all vehicles now have knock sensors. However, your performance will be reduced significantly.
For anyone that was wondering.
Just put the fuel the owner's manual tells you to put in folks.