This is not scientific, just real life observations. We have a 2017 2.3 Ecoboost Explorer and live in NJ. It's recommended MINIMUM fuel octane level is 87. HOWEVER to get the most POWER it's recommended to use 91 or higher. The first year of use we used 93, the only premium on the East Coast. As far as mpg we got ~1-2 mpg better with the 93 vs using 87 later on. The 93 did give better power when passing on the highway, not a lot though. My unscientific observation for the $0.50-60 more per gallon for premium is it's not really worth it in a non performance vehicle. My UOA's don't show significant fuel dilution differences using 87 vs 93, considering the seasonally different driving conditions. This is just my real life observations, other members may have different experiences. I welcome their experiences.
Whimsey
Whimsey