Drivers continue to face expensive fuel costs at the pumps, with drivers urging motorists to seek out the cheapest petrol and diesel prices in their local area.
Fresh data from RAC Fuel Watch shows that the average price of petrol has risen by almost 2.5p per litre, although diesel has fallen by 4.5p.
Drivers are now paying an average of 159.4p and 183.9p per litre for petrol and diesel, respectively, with prices fluctuating in May.
Petrol prices rising now means drivers are paying £1.32 more every time they fill up a standard 55-litre family car, bringing the total to £87.68.
While falling diesel costs have taken £2.50 off the price of a tank, drivers are still paying more than £101 for a standard tank, with larger vehicles paying even more.
The RAC put the changing prices down to changes in the wholesale cost of petrol rising mid-month, while the diesel equivalent fell.
On May 14, retailers were paying 123.5p for petrol and 133.3p for diesel, even though the gap in pump prices stands at a staggering 25p.
Simon Williams, head of policy at the RAC, acknowledged the massive price fluctuations, calling it a "better month" for diesel vehicle owners.
Experts have highlighted the fluctuating petrol and diesel prices seen across the UK in May
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He added: "Those relying on unleaded had to endure yet another rise at the pumps, while those who use diesel saw a welcome 4.5p reduction.
"It's really quite unusual to see the price of one fuel go up and the other come down. This was brought about by the wholesale cost of unleaded rising due to higher demand in the United States."
He noted that this coincided with a drop in demand for heating oil in western Europe, which is "refined from the same part of the barrel as diesel".
Mr Williams also highlighted "good news" for drivers after the price of Brent crude oil fell below $100 (£74.37) during the last week of the month.
Supermarket forecourts sold petrol and diesel at lower average prices than the UK average
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He suggested that retailers could have hiked prices even further, with forecourts deciding to keep the price of unleaded down at the expense of greater diesel reductions.
RAC data showed that shopping at supermarket forecourts will deliver larger savings, with petrol being around 4p cheaper per litre than the UK average.
Last month, the price of unleaded at the supermarket only rose by 1.4p compared to the national average of 2.4p.
The Competition and Markets Authority's recent report stated that retailers hadn't altered their pricing strategies during the Iran war.
Petrol and diesel prices spiked last month to their highest prices since the aftermath of the Russian invasion of Ukraine in 2022 | PADespite this, competition was lacking, and retailer margins remained at historically high levels, with experts warning that prices could continue to cause issues for motorists.
"We hope its next report shows that drivers have been treated fairly by retailers reducing their pump prices in line with the fall in wholesale costs," Mr Williams said.
During May, the Government announced that it would freeze the 5p per litre fuel duty cut until the end of the year in a bid to support drivers.
Under previous plans, the fuel duty cut, which was introduced after the Russian invasion of Ukraine, would be reversed by 1p in September, 2p in December and 2p in March 2027.