There was an unprecedented gap between the price of diesel and petrol at the pumps in the last week of September, according to the latest industry analysis.

Diesel was on average 17p more expensive than petrol on UK forecourts, when there is usually a much smaller gap between the two fuels. The average price of a litre of diesel was 180.22p, while the average price of unleaded was 162.96p. Over the last 20 years diesel has usually been around 5p more expensive.

The previous highest discrepancy was in August 2015 when diesel was 11p more expensive than petrol.

As the price of unleaded petrol has decreased from the highs of the summer months, diesel’s fall has not been as steep. Diesel’s resistance is mainly due to the war in Ukraine. The UK has imposed a ban on Russian diesel imports (the EU’s ban is not set to come into force until February), and previously a third of our diesel came from Russia. We are entering the peak period of demand for red diesel (gas oil) in Europe, so this will also have an impact.

Steve Gooding, director of the RAC Foundation, said: “In part this huge gap is the product of a dip in global demand for petrol following the end of the so-called driving season in the United States.”

“Given that supplies from Russia have been cut back because of the war in Ukraine this means there are a lot of people chasing less stock”, said Gooding.

“The bad news for UK diesel drivers – and the diesel-truck dependent UK freight industry – is that, with winter only just starting and the war in Ukraine showing no sign of ending, the sizeable gap between diesel and petrol pump prices is likely to continue for several months to come even if the cost of oil drops.”