Here's a helpful post.

If you're bothered about the petrol costs then use tesco 99 ron which is only 5p/litre more than whatever their normal unleaded price is. In comparison V power is always 7 p more than NU.

Even better is Sainsbury 97 RON at 3p above their NU price.

I use both in my FRS.

In fact depending where i am it may be tesco, sainsbury, v power, or esso. Only difference i ever notice is the price!