Thank you for the detailed explanation.

So is it fair to say engines that require higher octane fuel are not designed as well as engines that run fine on lower octane fuel since they can’t figure out how to run without knocking on the lower octane fuel?

“I’d put premium fuel in it, especially in the summer”

Is it just that the car doesn’t need it. (Sensors/computer will adjust injectors)

What’s different about summer?