I stick to proper petrol companies. Primarily Shell, i've 2 that don't take me out of my way to use. I always avoid supermarket fuel if i can help it but if im really short i'll put a tenner in until i get to a better place. The worst fuel i have used is BP for some reason. Not only is it dearer than all the others my car runs rough on it. Everything else is spot on and the fuel is the only thing i changed, but the car was really sluggish, 3rd gear corners were now 2nd gear corners. Last week it was shite after just £10 of the stuff. Ran like it for about 3 days. After a fill up of the normal shell and its running a treat.

Any links to some of the sites you found most useful? I'm interested to see if other people have similiar problems with fuel.