This would be a loaded topic. Did you join just to ask that question?
Hyundai ECU doesn't adjust very widely for octane, unlike many automakers'. Anecdotally, I've noticed more consistent power delivery on midgrade (89) but not additional performance nor should you expect additional performance.
I joined because I’m a new owner of a 2020 Elantra GT N line, I was just curious what every body else ran. I live in Colorado so the regular gas is 85 octane, I’ve been using 87 (mid grade out here) and just wanted to know if there was a difference with premium to mid grade. I wasn’t looking for performance with octane difference, just seeing if it was possibly more smooth with premium.
Mid-grade to most of the country is 89 octane. I know 85 octane is typical at elevation in Colorado but I would not run it in a car equipped with a turbo. The manual specifies 87 or greater. No allowances are made for elevation. I typically run 87 from Costco. I think I ran one tank of 91 and detected no improvement.
It is amazing to me that a boosted 1.6L car can even run on 87 craptane and still make 200+ hp.
Only ones that might take advantage of 91+ oct fuels are those running more boost via a tune or turbo upgrade
A higher octane does not mean the fuel is more powerful. Octane rating in gasoline is fuel's ability to resist engine knock (pre-ignition). Premium fuel however does contain more energy per unit in general because it usually has zero ethanol.
Not in Kalifornia....Our 91 oct has 10% ethanol due to it's oxygenation properties. The power from the higher octane is attributed to the fact you can run more boost and timing.
My Fiesta ST ran on 91 oct and was able to generate substantially more torque. I later tuned it on an E30 blend and it was a little rocket.