OK, I will accept Immingham is a special case!
The diesel here this morning at the local supermarkets (Tesco, Morrison) is 113.9 per litre. That's in mid Norfolk. The nearest refinery would be Immingham or Isle of Grain on the Thames Estuary.
The difference in price is supposed to cover the cost of distribution which links it to the distance from the refinery.
If you look at Stanlow on the Wirral and mid Wales or Grangemouth and the Highlands you find something similar.
With diesel you can get away with some jerry cans in the back of the car to supplement the stock in the main tank which you shouldn't do with petrol. My 4x4 has a 90 litre main tank but you can fit another 90 litre tank to cope with long trips across the Sahara or similar. With the opportunity to make a trip to a cheaper source of fuel it is sometimes worth combining the journey for fuel and normal shopping. Otherwise any saving in price is lost on the cost of the journey.
My other point was that you can modify some of the older diesel engined cars to use old cooking oil. The oil has to be kept warm and you need extra filters to protect the injection pump but it can work out as a very cheap way of running the car. See:-
http://journeytoforever.org/biodiesel_svo.htmlThe conversion isn't cheap and there are some risks (e.g. oil polymerisation). You can convert the old cooking oil into bio-diesel but the cost of soda and meths plus the cost of dumping a lot of glycol produced in the conversion usually make it a costly solution. Plus there is a risk of messing up the engine if you don't get the conversion process right.
All of which means that driving less, keeping the car empty of all unnecessary junk and developing a light right foot are still probably the best way of keeping the cost of motoring down.
Just my opinion
NN
Similarly with LPG for petrol engined car, if you fit a kit to match the car engine (e.g. multi-point injection for a recent fuel injected car engine) you can get good economy (normally 10% worse than petrol) and the engine wont need a new cylinder head every 60-80,000 miles (flashlube kit to avoid valve damage). The benefit of LPG is that it is cheap and enviromentally good.