[orm518]

Regardless of running 87 or 91 (obv make sure you use the recommended octane rating) make sure you’re using gas from a brand that uses good fuel detergents. Detergents make a big difference in terms of carbon build up.

Second the recommendation to use gas that has been awarded the title "Top Tier" see list of Top Tier brands.

In my Sorento non-turbo, I use Regular which is 87 in the northeast. No need to overpay.

When I owned a 2018 Kia Sportage SX with the 2.0 Turbo, I used Premium 93, even though only regular was recommended. A few cents a mile extra for peace of mind with a high compression turbo.

Off topic, but worth pointing out that you should read your manual, in my Volkswagen Passat with a 2.0 Turbo the owner's manual explicitly says using higher octane gas "may" result in higher performance. Some of the VW enthusiasts on another board I follow have shown on the dyno an increase over manufacturer's stated numbers using premium. Mazda also specifically posts two sets of numbers (227hp or 250hp plus 10 more lb/ft torque) for their turbo engine in the CX-5 with whether you use regular or premium gas.

It's about whether the manufacturer allows the engine's ECU to adjust specs with higher octane or if it locks it in for the minimum recommended. I do not know if Kia/Hyundai program their cars this way.