The average price of diesel and petrol increased by 6p per litre in May, the worst monthly rise in at least 18 years, according to RAC Fuel Watch data.   

Diesel increased by 6.12p – from 126.27p to 132.39p – the second worst rise since the start of 2000, when it rose by 8.43ppl 10 years ago in May 2008 (120.83p to 129.26p).

The May 2018 rise has made the cost of a tank of diesel for a family car £3.37 more expensive at £72.81.

Unleaded meanwhile, increased from 123.43p to 129.41p, taking the cost of filling up a 55-litre family car to £71.18 – an increase of £3.29 in just one month.

The RAC Fuel Watch data also shows the average prices of both petrol and diesel have gone up every single day since 22 April, adding 8p a litre in the process – the longest sustained price increase since March 2015.

RAC fuel spokesman Simon Williams said: “The rising oil price together with a weaker pound is a punitive combination for anyone that drives regularly.

“In the last week of May the oil price cooled a little to $76 a barrel which is slightly better news for motorists as the RAC’s two-week forecast is currently showing that average prices may even reduce by a penny or so.

“While this isn’t much, and could easily change in response to oil trading this week, it is at least a sign that the constant rise in forecourt prices may have stopped for the time being.”

In May the big four supermarkets raised petrol by 5.49p a litre and diesel by 5.88p while on the motorway, service stations added 6.37p to unleaded, taking it to 144.75p a litre, and 6.69p to diesel making it an eye-watering 147.80p a litre – 15p a litre above average UK prices for both fuels.

The forecourt increases have been driven by a jump in the price of oil, coupled with a weakening of the pound against the dollar. Oil broke through the $80 a barrel mark twice in May – something which has not been seen for three and a half years (since 12 November 2014).

Overall, May saw a 3% increase in the price of a barrel of oil (from $74.31 to $76.39) and a 2% drop in the value of the pound against the dollar ($1.35 to $1.33), making the wholesale price for retailers more expensive as fuel, like oil, is traded in dollars.

Williams said: “There is talk that OPEC – the Organization of the Petroleum Exporting Countries – may agree at its meeting on 22 June in Vienna to change its tack of restricting oil supply.

“The group, together with Russia, have been limiting production with a view to removing the long-term oil glut. This strategy has been successful and, as intended, caused the barrel price to rise. If a decision is taken to increase supply it may provide some much-needed relief for motorists at the pumps in the UK.”

Howard Cox, founder of the FairFuelUK Campaign, says that “greedy opportunistic oil speculators”, along with OPEC and Russia's oil production levels posturing, are using geo-political spats between the USA and Iran to “deliberately” over inflate the cost of filling up.

He said: "Businesses in the fuel supply chain are yet again exploiting the already highest taxed motorists in the world by not reducing pump prices when oil prices fall. They rise like a rocket and fall like a feather. As a consequence, inflation, GDP and consumer spending is being impacted badly by these greedy companies."

Regional fuel price variation

The North West experienced the biggest rise in petrol prices with a litre going up 5.98p in May to 128.72p. Northern Ireland saw the smallest increase at 5.07p a litre, although unusually their unleaded was not the cheapest in the UK as that honour went instead to the North East with a litre costing 128.24p at the end of May. The South East once again was the most expensive place to buy petrol with a litre averaging 129.83p.

Looking at diesel, drivers in Wales endured the greatest increase on the forecourt with a litre jumping by 6.07p to 132.03p. The North East and South East had the smallest rise at 5.66p, but a litre of diesel in the South East is the most expensive in the UK at 132.73p.

Regional average unleaded pump prices

Unleaded	01/05/2018	30/05/2018	Change
UK average	123.43	129.14	5.71
North West	122.74	128.72	5.98
East Midlands	123.24	129.20	5.96
Yorkshire And The Humber	122.57	128.42	5.85
West Midlands	122.99	128.80	5.81
Scotland	123.21	129.01	5.80
South West	123.55	129.35	5.80
Wales	123.18	128.88	5.70
South East	124.19	129.83	5.64
East	123.88	129.43	5.55
London	124.22	129.74	5.52
North East	123.09	128.24	5.15
Northern Ireland	123.32	128.39	5.07

 

Regional average diesel pump prices

Diesel	01/05/2018	30/05/2018	Change
UK average	126.27	132.06	5.79
Wales	125.96	132.03	6.07
Scotland	126.40	132.35	5.95
South West	126.48	132.33	5.85
Yorkshire And The Humber	125.46	131.28	5.82
East	126.74	132.54	5.80
North West	125.92	131.72	5.80
West Midlands	125.73	131.53	5.80
Northern Ireland	125.31	131.05	5.74
East Midlands	126.23	131.91	5.68
London	126.90	132.57	5.67
North East	125.65	131.31	5.66
South East	127.07	132.73	5.66