Do you also run a bottle of injector cleaner, or 10K Boost, or EGR cleaner, or any one of other much more potent cleaners through the car system as well? They will make a billion times more difference than switching from supermarket to premium fuel will.
Not saying I completely disagree with your logic: Indeed, I sometimes run a tank of 97 in the MR2 instead of the usual supermarket 95 for a similar reason, but then I also back that up with a good dose of the hard stuff once in a while.
In my daily I do as that's mainly run off supermarket fuel so now and again I add injector cleaner and a tank of premium fuel.
However as I use vpower all the time in the zed and I am confident on the quality and cleanliness of the fuel I do not feel a need to supplement that.
I am assuming from your comment you've done some sort of experiment to prove this? Or at very least run your zed (when you had one) on vpower for a prolonged period of time and then put your additives in and immediately noticed a difference?
The reason I use vpower is I believe through my own research that it is the most pure fuel you can buy from the pumps. And because of this reason, I feel there is no need to put additives in to the fuel tank of my zed.