Midnightsun
Been here awhile...
My bad, all along I assumed you had a sedan R spec like me with a real engine.
Just noticed you are driving the coupe 3.8 which is tuned for premium and in fact is the only recommended fuel. My comments were to people running the 3.8 sedan which recommends regular however some don't even believe the manufacturer because they have yet to understand marketing. In my 5.0 R spec, both fuels are recommended and I can tell you the slight increase in performance is not noticeable at all. On a race track, just the humidity/temp difference would negate 7hp on any given day. Even if it does get slightly better milage on higher octane it will never be the most cost effective gasoline in my car. I hope you forgive me as I really do not want to burn in hell doused in ethanol. 
The way I see it is only the Tau that I know of recommends both fuels. This means they have no issue regarding longevity or warranty by using either which may not be the case in cars run on a fuel which is not the recommended.


The way I see it is only the Tau that I know of recommends both fuels. This means they have no issue regarding longevity or warranty by using either which may not be the case in cars run on a fuel which is not the recommended.