In the owner's manual:

Petrol Engine
Unleaded

For Europe
For the optimal vehicle performance, we recommend you to use unleaded petrol which complies with EN 228 and has as octane rating of RON 95 (Research Octane Number 95)  / AKI 91 (Anti Knock Index 91) or higher.

You may use unleaded petrol with an octane rating of RON 91~94 / AKI 87-90 but it may result in slight performance reduction of the vehicle.

Except Europe
Your new Kia vehicle is designed to use only unleaded fuel having an Octane Rating of RON 91 (Research Octane Number 91) / AKI 87 (Anti Knock Index 87) or higher.

Your new vehicle is designed to obtain maximum performance with UNLEADED FUEL, as well as minimize exhaust emissions and spark plug