I'm with you Biggles, I dont need no ithingy to tell me where a fuel stop is as you can usualy find one on your side of the road....
I use what ever is the cheapest in a convenient radius, or what ever is around when fuel is needed.
BP in my area is usually way more expensive than the other servos
Google maps/navigator on my Android devices will show all fuel stations around you, it comes with the device and works well.