Right, this is fairly boring but I decided to see if Vpower made any difference to fuel consumption. I know the other benefits of using a higher RON fuel. But performance benefits are subjective at best whereas fuel consumption is easy to measure and over a long distance it is accurate.
I drove about 3400 miles using 10 tanks of shell Vpower then using normal shell petrol I used another 10 consecutive tanks.
The difference in consumption was 0.54%. No difference at all.
I have since switched back to using Vpower because I like putting the best into my car. Being an engineering nerd I wanted to put some numbers behind the choice.