The AA has praised the supermarkets for keeping fuel prices low and says their policy has helped them win market share from other fuel retailers. Supermarket petrol sales between April and June this year are down only 0.2% compared to minus 4.8% for non-supermarket retailers.

In its latest monthly fuel price update it says average unleaded petrol prices fell for the fourth month in a row, dropping from 111.16ppl in mid September to 109.21ppl in mid October, compared with a peak of 117.28ppl on June 22. Diesel began to edge up slightly from 11.41ppl to 110.96ppl, but the AA says retailers have cut their margins on diesel. It points to the current 2ppl differential with petrol, which reflects the differential at the wholesale level, compared with a 5ppl differential at retail level in the winter when the wholesale differential was only 3ppl. The report adds: "Strong competition among supermarkets has helped to keep the lid on prices. The ’big four’ have now put significant price distance (an average 2ppl on petrol and diesel) between them and their non-supermarket rivals."

AA president Edmund King said: "Supermarkets have done a good job this summer in keeping the pressure on pump prices and, so far, they don’t seem ready to ease up."