I'm a total V Power convert. However, be careful. Normally V Power is around 6p per litre more than 95 unleaded, occasionally however you will find a Shell garage that charges as much as 11p more per litre.
I never buy V Power at a motorway service station, simply way too expensive (Actually I never buy anything at a motorway service station for the same reason)
I am cautious about other premium fuels like BP Ultimate, same price as V Power but not nearly as good, 97/98 ron instead of 99. Some supermarkets have a good 99 ron petrol.
Some years ago before V Power replaced Optimax, I was in a focus group where Shell were trying to assess how much they could charge for V Power. Prices as much as 20p over unleaded were bandied about
I have to hold my hands up and mention that I also buy Shell as I am an avid Air Miles (Avios) collector