Unless tuned to the position where the engine can use a higher octane rating (high compression head, ignition advance, race cams etc etc) then it is wasted money. In standard tune it won't make any difference although you might think it does. Placebo effect blah blah.
Have played a lot with this on my modified Caterham 7 to find rolling road results etc. with programmable ECU, wilder cams, oversize valves and fully ported, skimmed head, throttle bodies, modified injectors etc etc Difference was 4 bhp up at 8,000 rpm (200+ bhp) with Optimax. In the grounds of RR error.
I use whatever petrol station is within five minutes of 'the light' coming on Chris !!! Paranoid? Me? Yep. The VTR seems like a right old lump to push anywhere.
I used to use 100LL in a car. Yep. One hundred octane low lead
It was used in a Triumph 1500 with 65bhp. Why you ask? Well as an aircraft engineer we had to often drain down tanks and were unable to use the fuel again so it had to go somewhere!!! All for private airport and restricted land use of course; ahem!!!
I even used to dilute it with what was then two star. Often had the pump person use the speaker to tell me I should be using 4*.
