Petrol drivers are still getting a raw deal at the pumps despite a record price drop in August, the RAC has argued.

Although a further 12.31p came off the average price of unleaded last month, the RAC said it should have dropped much further

Although a further 12.31p came off the average price of unleaded last month – putting the average price under 170p (169.8p) for the first time since May – the RAC said it should have dropped much further.

In fact, it believes average forecourt petrol prices should actually be around the 161p mark after the average weekly delivered wholesale price fell to reach just 124.08p last week. And this allows for a significant retailer margin of 10p per litre

The last time the delivered wholesale price of petrol was at its current level was in late April, when retailers were charging on average around 162p per litre.

Diesel pump prices, however, remain a fairer reflection of wholesale prices. A total of 8.35p came off the average price of a litre in August, ending the month at 183.71p. This means it now costs £4.59 less to fill a 55-litre car than it did a month ago, with costs down from £105.63 to £101.04.

The RAC also warned that supermarkets, traditionally the cheapest for fuel, still don’t necessarily have the lowest-price unleaded at the moment.

The biggest supermarkets were charging just 1.62p below the average price of petrol last month (168.18p), compared to the typical 3p. Instead, the independents continue to lead the way, undercutting prices and charging “fairer” levels for fuel.

And supermarkets in some parts of the country appear to be charging much more for the same fuel than in other areas.

RAC spokesperson Rod Dennis said: “There’s a real postcode lottery out there, with prices varying wildly depending on where a driver is in the country. Drivers must shop around for the best deal they can, and we applaud those independent retailers who are doing their best to charge a fairer price for fuel and support their local communities through this incredibly expensive time.”

He also warned that dark clouds are beginning to gather once again for prices.

The cost of oil – the biggest contributor to wholesale petrol and diesel prices – fell significantly in August, down $7.67 to end the month at $92.36. But OPEC+, which represents many of the biggest oil-producing nations, may choose to cut production at a meeting next week. If it does, oil prices may begin to rise once again.

Sterling also had its worst performance against the US dollar in August since October 2016, with a pound worth just $1.16 by the month’s end, which – as fuel is traded in dollars – makes it more expensive to purchase on the wholesale market.

Analysis by the RAC in August also revealed that the UK is one of the least generous countries when it comes to supporting drivers with high petrol and diesel prices.

Rod Dennis continued: “We urge the incoming Prime Minister to heed our calls for more financial assistance for drivers, such as a deeper cut in fuel duty, and to look carefully at the much more generous packages of help being offered to those in other countries across Europe.”