A litre of unleaded petrol now costs 142.57p on average at the pumps, a price not seen since the end of October 2021.
It is around 10p a litre cheaper than in the run-up to last Christmas, but diesel prices have not fallen.
RAC fuel spokesman Simon Williams said the drop comes during one of the busiest times of year on the roads.
He said: “This is good news for drivers, especially as prices should continue to come down in the run-up to Christmas due to the wholesale price being significantly lower.
“While the biggest retailers haven’t announced any headline-grabbing big cuts, prices are falling steadily every day which is encouraging.
“We just have to hope this continues in the coming days.
“If wholesale prices are reflected more fairly at the pumps, we should see the average price of petrol drop below 140p in the next week.
“While diesel isn’t at similar low point – as it averaged of 6p less than its current 150.29p in August – it’s still down from last Christmas’s dizzying prices of around 175p a litre.”
