, the mileage isn't bad, but it is premium gas.
Recommended or required ?
Dunno. In my mind the two words mean the same. In other words, I always have used premium gas when an engine calls for it as the performance, economy and engine internals all benefit. I also avoid ethanol whenever possible, and only go to Ultramar if one is available for that reason. I have a snow blower that uses regular but if that gas is used, the carb gums up from the ethanol to the point where it will barely start after 2 seasons, and will not after 3.
From the user manual " use premium unleaded gasoline with a posted octane rating of 91 or higher. You can also use regular unleaded gasoline rated at 87 octane or higher, but the vehicle's acceleration could be slightly reduced ". I guess that means "recommended", but I suggest reading it as "required"