The average price of a litre of diesel and petrol at UK filling stations fell by 6.69p and 8.74p respectively during July, according to RAC data.

The motoring organisation said these were respectively the fourth and third biggest monthly reductions seen during the last 20 years, leaving diesel at 192.38p and petrol at 182.69p.

However, the RAC said this still didn’t reflect changes to wholesale fuel prices, based on which it said diesel should be at 182p per litre, and petrol at 167p.

RAC spokesman Simon Williams said: “July has been an unnecessarily tough month for drivers due to the big four supermarkets’ unwillingness to cut their prices to a more a reasonable level, reflecting the consistent and significant reductions in the wholesale cost of petrol and diesel.

“As it was, we saw independent retailers leading the charge with fairer pump prices appearing all around the country which eventually forced the supermarkets to finally implement a more substantial cut late last Friday afternoon (29 July).

“What ought to have happened is that the biggest retailers cut their prices more significantly on a daily basis, given the wholesale price of petrol has fallen steadily over the last eight weeks. Instead, average retailer margin for petrol across the industry has been up around 20p a litre for the last two weeks – more than three times its long-term average.

“The average cost of delivered wholesale unleaded in the first week of May was 131.73p which gave rise to forecourt prices across the country hitting 167p a week later. Wholesale petrol averaged virtually the same last week which should – if retailer’s pass on the savings they’re benefitting from – in theory bring pump prices down to a similar level to what we saw in mid-May.”