Drivers shelled out 114.88p for unleaded in August, up half a penny in the month, while diesel increased by a third of penny to 118.47p.

While prices have crept up in the three months to August, according to RAC Fuel Watch, it said both fuels are still 13p cheaper than they were at the start of the year (128p for petrol and 132p for diesel).

Supermarkets still offer drivers the cheapest pump prices – around 4-5p less than other forecourts – though they have increased slightly to 109.55p and to 114.17p for diesel.

Asda started the month of August as the lowest cost supermarket petrol retailer but by the end of the month, Morrisons had edged marginally lower at 109.24p compared to Asda’s 109.43p. On diesel, however, Asda was a penny a litre cheaper than its nearest rival, Morrisons, at 113.35p.

The RAC data also revealed that motorway fuel prices “bucked the UK trend” as they stayed the same in August with a litre of unleaded setting drivers back 124.03p and diesel 129.33p.

The difference between filling up at a motorway forecourt station is currently 10p more expensive than the UK average (9.15p – petrol; 10.86p – diesel) which the RAC said is “considerably lower than January” when the gap stood at around 20p a litre.

This is 5p a litre lower than the average over the last five and a half years, with RAC data indicating that over this period motorway fuel usually commanded a premium of 15p above the UK average petrol and diesel prices.

‘Pump prices not ominous for UK drivers’

RAC fuel spokesman, Simon Williams, said despite pump price rises, drivers have been spared any nasty shocks when they come to fill up as coronavirus lockdown measures eased and more people hit the road.

He said: “It was good news for drivers that August didn’t see the price of fuel jump, especially as so many people were ‘staycationing’. It was also positive that motorway fill-ups remained more reasonably priced than they have been in the past with service station retailers apparently not taking as much margin as they have in the past.

“The RAC is aware that Moto is experimenting with selling fuel that’s only a few pence a litre above supermarket prices. Its small number of trial sites were selling petrol at 111.9p and diesel at 115.9p at the end of August – only 2p higher than the supermarket averages and around 3p less than the UK averages. While it’s unlikely this trial – as yet – signals an industry-wide change of direction regarding fuel prices it won’t have gone unnoticed by its competitors so there’s a chance that service station prices may be lower than they would otherwise have been.”

Williams added that the short-term outlook for pump prices “does not appear ominous for UK drivers” despite a blip in the oil price at the end of August.

“The cost of a barrel of oil rose dramatically due to fears of a hurricane affecting supplies in the Gulf of Mexico, but fortunately there was no adverse impact to production as the hurricane was downgraded to a tropical depression and refineries were spared massive flooding.

“Our pump price forecast for the next fortnight shows petrol should come down by a penny while diesel ought to fall by around 5p a litre if retailers play fair and reflect the downward movement in the wholesale price properly,” he said.