Despite the average price of petrol falling by more than 5ppl in November, the biggest monthly drop since January 2015, the RAC claims prices should fall by at least as much again.

RAC Fuel Watch shows unleaded petrol fell from 130.61ppl to 125.43ppl (down 5.18ppl) in November and diesel dropped 2.5ppl from 136.93ppl to 134.42ppl.

However, RAC fuel spokesperson Simon Williams said: “The oil price plummeted by 24% throughout November which proved to be positive for motorists – indeed we haven’t seen such a large drop in average prices in nearly four years. Having finished October at $75, a barrel of crude ended the month only costing $57 which sent wholesale prices tumbling even though the value of sterling dropped by 2%.

“This should have translated to the average price of petrol being around 120ppl, but retailers chose not to pass on the savings meaning the current average still remains unnecessarily high at 125.43ppl. While one of the big four supermarkets has consistently cut the price of unleaded the others haven’t by as much which has meant the UK average price didn’t drop as much as it should have done.

“Based on our data, petrol still ought to come down by 7ppl in the next two weeks and diesel by 5ppl.

“In the last six years we haven’t seen retailers take this much margin from selling a litre of petrol over such a protracted length of time. For some time prior to this we had been happy to praise retailers for passing on wholesale savings on the forecourt and say there was little evidence of ‘rocket and feather’ pricing. Now, however, there is very clear proof that many retailers are operating ‘rocket and feather’ policies.”

On 29 November the average price at the big four supermarkets was 121.27ppl for petrol and 130.96ppl for diesel. Motorway services have been slower to reduce their prices, and were charging an average of 145.40ppl for unleaded petrol and 153.70ppl for diesel. On 20 November, the average price of diesel at services reached 155.40ppl which matched the previous high of April 2012 when average fuel prices across the UK were at record levels.