The first time I pumped 93 Octane into my tank I noticed the MPG numbers in the dash made a big change after driving my FGT for a couple of minutes. I assumed this was because the ECU determined the octane change.
Don't know if the ECU does this, like the Elantra N, but I got a kick out of the MPG changes.

 

I wondered the same thing. I just picked up my '23 GT2 Monday and I'm about at the end of my first tank, which I'm sure is 87 as the dealer filled it up. I definitely plan on running 93 the majority of the time, as I've had to run it in all my other vehicles over the past 7-8 years, so I'm use to that bill. Have you tried it yet? If so, what's your thoughts?

 

I am not sure what to think, this powertrain is so finicky to weather conditions, temp, humidity, air density etc. I swear my car is a woman since I never know what to expect for power, each day is a new surprise. I just went cheap on the last tank of fuel and put 87 in, I don't think it has ever felt this strong. Is it weather or fuel or is my ECU really an "artificial intelligence" that has good and bad days?

 

Maybe a woman AI?

 

Here in the north we get Winter Blend and Summer Blend. I noticed on my Fieros that the gas mileage would drop in the winter with winter blend. That happened with the 2.5L 4 cyl. , 88 5 speed or the 87 GT with 3800 SC V6 and auto.
I just turned over 7k on the GT and I have been using 93 octane for a while now and find the car is more responsive and makes power up to red line now.