Is it safe to run premium in my 2015
5.7 L challenger or only 89 octane I
ask because I like to run premium it
the only thing you can buy that is no
you can run premium , I don't think ethanol will hurt that motor being a 2015 . I spend extra for the premium blend for the same reason , I have older cars/trucks and don't want the ethanol . And I guess if no one buys it there won't be any for the small engines . The ethanol is a cheaper oxygenator than what's used in the higher octane .
Not knowing which engine you have, look at the specification next to the filler cap or in the owners manual; by your question, it's probably 87 Octane or E10. The car was designed for Ethanol/Petroleum fuel, so you should use it. Ethanol-free gasoline won't do anything for your car except get you a little better economy and this would be offset by the lower economy you'll get from running higher Octane. Running an Octane rating higher than what the engine is designed for, in addition to costing you more for the gasoline, can cause minor problems as the computer constantly senses the Octane and quality of fuel and won't readily recognize an increase over 87.
I don't like ethanol but I would use premium anyway in such a car. If you ever store it for an extended period of time fill it up with 100% gas.