Data from RAC Fuel Watch has found that supermarkets are currently enjoying margins of about 15p a litre on both petrol and diesel.
It says that wholesale prices for petrol have fallen by 13p per litre since their October high and diesel prices have fallen by 22p, but these decreases haven’t been transferred to supermarket forecourts.
The average price of diesel bought at a supermarket has fallen only 3p a litre while petrol has only gone down 4.4p.
RAC fuel spokesman Simon Williams said: “With many people struggling to put fuel in their cars it’s very sad to see the biggest fuel retailers taking advantage of their customers by charging far higher prices than they should be. This is unfortunately a perfect example of prices falling like a feather, the opposite of them rocketing up as soon as the wholesale price rises significantly.
“The supermarkets dominate UK fuel retailing, primarily because they have traditionally sold petrol and diesel at lower prices due to the large volumes they sell, but sadly there is now a remarkable lack of competition among the four main players which means prices are far higher than they should be.
“We urge the supermarkets to do the right thing by their customers and cut prices by at least 5p a litre immediately.”
