The price of petrol in the UK has fallen for the fourth successive month, according to RAC Fuel Watch.

It reported that the average price of a litre of unleaded petrol fell by half a pence (0.48p) to 125.93p in November, while diesel fell by a similar amount from 130.27ppl to 129.83ppl. Diesel has fallen for three out of the last four months, having recorded a small increase in September.

Since early August when the average price of petrol was 129.24ppl, the average price has dropped by 3.31p a litre. The diesel reduction was a penny less at 2.21p, falling from 132.04p.

The average supermarket price of petrol at the end of November was 121.20ppl, down 1.74ppl in the month, and diesel was 125.15ppl, down 1.41p. Both fuels at supermarkets are now 4.7ppl cheaper than the UK average.

At the end of November Asda was selling the cheapest petrol at 119.70ppl – 1.77ppl lower than its nearest rival Tesco. It was also the cheapest on diesel with a litre 1.68p cheaper than Tesco. Sainsbury and Morrisons were around 2p more expensive than Asda on diesel.

RAC fuel spokesman Simon Williams said: “Due to savings in the wholesale price of both fuels Asda led a round of supermarket fuel cuts in late November which the other three major retailers followed.

“Despite this knocking off about a penny and half from the average price of fuel charged at the four big supermarkets, the UK average only reduced very slightly. This implies that other retailers haven’t followed the supermarkets lead and are not passing on savings in the wholesale price.

“Normally, the supermarkets are about 3p a litre cheaper than other retailers so seeing this go out to 4.7p is definitely a sign something’s different. If drivers are aware of this difference, it’s only going to lead to them heading to the cheaper supermarket forecourts and the smaller retailers losing more market share to their bigger rivals who are already responsible for selling 45% of all fuel.

“Looking at the wholesale price of both petrol and diesel retailers of all sizes should be cutting at the pump. As it stands, unleaded should come down by 5p a litre and diesel by 4p. We would like to think retailers are about to pass these saving on in the expensive run-up to Christmas.”

The price of oil fluctuated throughout November from a low of $61.96 to a high of $65.37 at the start, averaging $62.91. The pound dollar exchange rate changed very little over the month, starting and finishing at $1.29.

Simon Williams added: “As for what’s likely to happen with fuel prices going into next year, much will depend on the outcome of OPEC’s (Organization of the Petroleum Exporting Countries) meetings on Thursday and Friday. As it stands the organisation’s deal with Russia and other non-OPEC countries to cut supply by 1.2m barrels a day runs out at the end of March.

“With Brent crude trading consistently around the $60 mark the chances are the current agreement will be extended to the middle of next year when OPEC meets again. But there are concerns about weakened demand, with the ongoing trade dispute between the US and China still not resolved coupled with the US still producing strongly due to the continued contribution of its fracking rigs.”