It’s very simple and easy to use. You’ll need to register, then once you have you can 20 searches a week. You enter the post code of where you want petrol and it’ll bring up a simple list (see picture). It’ll probably show the five cheapest within a certain radius that you can set. In cities, the lowest is 2 miles, but outside the minimum is 5 miles.
So there you go, start saving each time you fill up!