Palladium said:
placebo effect, I have tried them all, no difference. just use regular in my 911, its cheaper and no different to super...........not imagining it, 30 years behind my conclusion.
Octane isn't something intangible - it's real. Your 911 would (if the management system didn't pull timing) be detonating under high load due to the lower octane fuel that you are putting in it.
My other car is turbo-charged where this is a short road to a new engine as the ECU can't pull timing fast enough, in an NA I imagine (note: assumption) that you're just getting lower power and mpg.
This sort of thing I do find hard to understand - you buy an out and out sports car with ~300 bhp, then for the sake of a couple of quid you give it fuel that will only allow you to see ~250 of the bhp you've paid for.
To the OP's point, I use V-Power when I can, but I've found that the supermarket stuff is ok, I'm seeing ~380 out of 2.3 litres with no det on the Saino's fuel, which suggests it does what it says on the pump.