Has anyone noticed whether different grades of fuel give them better economy?

I've been using Sainsburys/supermarket own 95 RON and have struggled to get much more than 250-260 miles out of any tank (I'm now on my 4th in a little under 1000 miles), which I don't think is particularly great. I do have a nightmare 10 mile stop/start commute twice a day, but I thought I could still return upwards of 30mpg.

Has anyone noticed whether Shell Optimax or BP Ultimate gives them better results? I know its a few pence extra per litre, but if it'll give me a better range out of the tank then its evens.