Hi Streak
Have been keeping track of my fuel usage since I first got the ST in Dec 2011.
Before I started using PM800 I only used Premium Unleaded.
50 fills before PM800 including trip to Blackheath Average 17.94 klm/lt (50.67 Imp MPG) For a total of 16,472.8 Klm Using Premium Unleaded (8 to12cents per litre dearer)
12 fills so far using PM800 and Standard Unleaded Average 17.91 klm/lt (50.59 Imp MPG) For a total of 3,325.6 Klm Extra cost per litre for PM800 3.5c
Savings for me using Pm800 4.5 to 8.5 cents per litre.
It is very hard to say if there is any improvement performance wise but I am happy just with the savings and the convience of using Unleaded.
Any performance gains, cleaner injectors or other benifits are just a bonus if they happen.