Only on the Turbo, otherwise none. As for anyone's past experiences, readings, consumer reports, or other 'experts' on the value or not of premium, remember, this is a different story with the Turbo as it really is designed to have different outputs based on the fuel. I'm sure this thread will go off the rails with info on octane, knocking, predetonation, waste of money, engine 'learns', as well as other non sequiturs, but remember this turbo actually is engineered to work different. but for your NA CX-30 - no difference
I've tried running one tank full of premium in my 2020 CX-5 (normally aspirated 2.5L) and got *zero* extra power out of it. Might be my imagination but I think the car felt even a bit less peppy. I do know it got slightly less gas mileage, which makes actual physical science sense, because premium unleaded (at least the blends distributed around here) contain a higher percentage of ethanol blended in than regular unleaded gasoline and ethanol has less BTUs of energy than the base gasoline.
And the winter blend premium unleaded gasoline in my area (near DFW north Texas) likely contains the full 10% or higher amount of ethanol because I can smell it when filling up, kinda like vodka, and regular unleaded doesn't.
So in my pseudo-scientific, anecdotally-empirically deduced opinionated experience.... if you don't have the turbocharged motor stick with regular unleaded, it'll likely give you both the best performance and fuel economy in normal driving conditions.
I have had a car in the past run better on mid-grade gas, but never any performance improvements. Just fewer knocks and smoother engine sounds. For my CX-30, I just stick to good ol' 87 octane and it runs fine.
According to Mazda, 93 octane gets you from 227 hp to 250 hp but, the cross over is at 4,000 rpm. The torque remains the same for 87 or 93 octane. Someone posted a plot which graphed the two different fuel vs HP & Tq. Ed