The average prices of both petrol and diesel hit new record highs in October after rising by nearly 7.5p and 8p respectively – with the price of unleaded rising faster than in any month since 2000.
The 21-year high added £4 to the cost of filling up a 55-litre family petrol car, which will now set the average driver back £79.39.
The increase in diesel added £4.50 to the cost of a diesel car - now £81.37 - compared to the start of October.
On October 24, petrol exceeded the 142.48p a litre all-time peak set on 16 April 2012 by reaching 142.94p.
Since then the price has continued to rise, finishing the month at 144.35p and up from 136.92p at the start, RAC Fuel Watch data shows.
Diesel also surpassed its record price of April 12, 2012 (147.93p) on the last day of the month with a new high of 147.94p, up from 139.78p on October 1.
The October hike in the price of unleaded is the largest since 2000 at 7.43p while diesel’s 8.16p increase is second only to the 8.43p jump seen in May 2008.
The previous biggest petrol price rise in a single month was in May 2018 when a litre went up 6p to 129.41p.
Both petrol and diesel are now 30p a litre – 26% – more expensive than a year ago.
This means it costs £16.50 more to fill up a family car with either fuel than it did at the end of October 2020.
Oil rose by nearly $5 a barrel (6%) from $78.62 to $83.47 last month, although on October 25 it peaked at $86.16.
This caused the wholesale price of a litre of unleaded to go up by 5p and diesel by 4.5p which is in stark contrast to the 7.5p and 8p forecourt rises.
But the RAC said the big four supermarkets were also to blame for the rises.
Collectively, they upped the price of unleaded by more than 9p a litre and diesel by more than 10p to averages of 142.18p and 145.28p respectively.
Asda had the cheapest petrol at 140.98p, only slightly lower than Sainsbury’s at 141.68p. Sainsbury’s, however, offered the lowest price diesel at 144.37p, just slightly less than Asda which charged 144.57p at the end of October.
The average price of motorway petrol was 158.43p on 31 October, with a record price set the day before at 158.56p. Diesel closed October at a new all-time high of 163.08p.
RAC fuel spokesman Simon Williams said: “October 2021 set records for all the wrong reasons and was a horrible month for drivers with both petrol and diesel prices hitting new heights.
"The increases of almost 7.5p being added to a litre of unleaded and more than 8p going on to diesel are some of the highest we’ve seen in the 21 years we’ve been tracking fuel prices.
“With a fill-up costing £16.50 more than a year ago, the impact is definitely being felt in homes up and down the country. It’s also bound to have a negative effect on the economy.
“There is, however, a glimmer of hope that the oil price may have peaked for the time being, but much will of course depend on whether more supply is released when oil producer group OPEC+ next meets on Thursday.
“Regardless of this, the profit margin retailers are taking on each litre of petrol is greater now than it used to be prior to the pandemic, which is artificially making forecourt prices higher, particularly as VAT is charged on top.
"We urge the biggest retailers, in particular, to play fair with drivers and ease the burden at the pumps by lowering their margins on petrol from around 8p a litre to more normal levels."
The motoring body's Fuel Watch data reveals petrol prices in Northern Ireland are almost 3p a litre cheaper than the South East of England where prices are higher than anywhere else.
“A litre of diesel in Northern Ireland is 144.36p – the same as the average price of petrol across the UK. In the North East diesel rocketed by a frightening 9p a litre to 147.22p,” Williams added.
