Drivers have been warned not to assume that the supermarkets are always cheapest for petrol and diesel.
Motoring organisation the RAC has called out the "Big Four" grocers - Tesco, Asda, Sainsbury's and Morrisons - for not cutting fuel prices quick enough.
The RAC said last week that wholesale price of petrol was back down to the levels recorded in early May of 131.75p per litre.
