I've just been mailed this and it looks like a good idea on the surface. Judge for yourself by reading their website.
I must admit I'm a bit fed up with the constant raising of fuel prices in the UK. And whenever you tell the Americans how much we pay for fuel they laugh at us for tollerating it. Well I'm glad to see that "Dubbya" is getting some heat for the U.S. folks having to pay a minute 50-60pence per litre, as apposed to the 97-104pence per litre we are currently paying.
You may also want to check out this lot too. Very useful site that mails you how much the cheapest petrol in your area is each week.