The average price of petrol fell by 2p a litre in October, bringing an end to a four-month run of rising prices, but leaving fuel still “seriously overpriced” at the pumps.

Both petrol and diesel pump prices are more expensive than they should be, the RAC analysis reveals

A litre of unleaded fell 2.6p from 157.12p to 154.53p last month – but it should really be on sale for around 145p according to RAC analysis of the wholesale market.

Diesel, which came down by a penny to 161.4p in October, is also more expensive than it should be and ought to be selling for 156p a litre.

Once again, it’s the independent retailers who are proving the champion for drivers, undercutting supermarkets.

Independently run Grindley Brook Garage, located at Whitchurch in Shropshire, is charging just 140.9p for petrol – nearly 14p less than the UK average, which is equivalent to a saving of £7.50 a tank, but also 11p less than the UK average for supermarkets.

The fuel finder feature in the free myRAC app also reveals three other independent retailers within five miles selling petrol for well under 150p – 5p less than the UK average. Diesel at Grindley Brook, run by DA Roberts, is 151.9p – nearly 10p less than the UK average, a saving of more than £5 on a complete fill-up.

But venture to the nearest town of Nantwich, just 13 miles away and with two supermarket retailers, and the cheapest petrol within five miles of the town centre is 152.9p – 7p more than around Whitchurch – and the lowest priced diesel is 159.9p, which is 4p less than the average near Whitchurch.

In Northern Ireland the average price of petrol on 31 October was 150.02p – 4.5p less than the UK average, while diesel is 157.48p, 4p cheaper.

Membership-only retailer Costco meanwhile is selling unleaded for an average of 141.7p at its 20 sites – 13p below the UK average and with the lowest price being 138.9p in Birmingham. Its average price for diesel is 151.7p – 10p less than the UK average, but its Derby site is selling for 148.9p.

In stark contrast the average prices charged at the big four supermarkets nationally is 151.72p for petrol – down 2.3p in October – but almost 11p more expensive than independently run Grindley Brook in Shropshire. Supermarket diesel ended October at 159.24p, up nearly a penny in the month, but more than 7p dearer than Grindley Brook.

RAC fuel spokesman Simon Williams said: “While four months of rising petrol prices came to an end in October, it’s definitely no cause for celebration that the drop was only 2p a litre as our data shows it should have been far greater. Instead, drivers will be outraged to learn they are still not being charged a fair price at the pumps by the big four supermarkets which dominate UK fuel retailing.

“This is dramatically demonstrated by the fact that one small independent retailer in rural Shropshire is selling petrol for 11p cheaper than the supermarkets. “

Williams added that the RAC data showed the supermarkets, as with all fuel retailers, are benefiting from lower wholesale costs but aren’t passing these onto customers – that’s despite the Competition and Markets Authority’s investigation concluding in the summer that the supermarkets had overcharged drivers by £900m last year.

He added: “Every day the supermarkets put off reducing their prices to fairer levels that reflect the lower wholesale market, is another day of extra profits for them, and another day of drivers having to fork out more money than they should have to for their fuel. This is all made worse by the fact that fuel duty is currently being discounted by 5p a litre to ease the burden on drivers in the cost-of-living crisis – a duty cut that drivers simply aren’t benefiting from.

“We highlighted these issues to the CMA, the Treasury and the Department for Energy Security and Net Zero last week, so were pleased to see that Energy Secretary Claire Coutinho has written to retailers making it clear they must pass on savings to drivers otherwise she will name and shame them.”