I have owned my 2009 FPV GT since new and the only fuel used is Caltex premium 95 or 98. The car has always run underpowered, pinging and generally unwell.
It has always been regularly serviced by Ford but have never been able to find the issue, not until i took my vehicle to a performance shop that specializes in Ford performance vehicles, i asked to have the car dyno tuned to find the issue but the owner of the shop asked what type of fuel i had been using, after telling him Caltex premium he said that was the problem.
To prove the point he put the car on the hoist and removed the fuel filter, to my disgust he was right, the fuel that came out was black. He suggested that i use BP Ultimate and to call him back after 3 tank fulls, the result is that the pinging has stopped, the car has more power and I am now getting over 100km more per tank. I'm now getting about 500km per fill where as in the past 4 years the best was approx 390km.
Quit frankly I'm disgusted that your fuel is so sub par but I have been paying top dollar with my Starcard, I hate to think the damage your fuel has caused to the engine, I have a photo of the fuel for your reference.