Unleaded petrol prices rose by 5.4p a litre in April 2019, which is the second-worst monthly price rise in almost two decades of records.
RAC Fuel Watch analysts say this has added £3 to the cost of filling the tank of an average petrol car.
How to find the cheapest diesel and petrol near you
The average price of petrol is now 128.1p a litre, up from 122.6p at the start of the month. A 5 percent rise in the cost of a barrel of oil is the cause, says the RAC: fuel retailers have quickly passed this on to motorists.
The scale of April 2019’s monthly price rise has only been topped once since 2000 – when petrol prices jumped by 6p a litre during May 2018.
It is also the third consecutive month of petrol price growth: back in February 2019, unleaded was down at 119.5p a litre.
“Despite the good weather, April turned out to be one of the bleakest months ever for drivers,“ said RAC fuel spokesman Simon Williams.
“RAC Fuel Watch data shows the price of unleaded rose every single day from the end of March, for three and a half weeks.
“This will have a damaging effect on household budgets across the country, and will inevitably mean there will be less money available for non-essential spending.”
Diesel subsidising petrol?
Diesel prices increased by 3p a litre during April 2019, taking the price up to 133.7p a litre.
However, the RAC has observed that the average difference between diesel and petrol wholesale prices was only 1p a litre during April, despite diesel costing 6p a litre more than petrol at the forecourts.
“It is very clear,” said Williams, “that retailers have been using the cheaper wholesale cost of diesel to subsidise petrol pump prices.
“Had they not, a new monthly price rise record for petrol would have been set.
“Diesel drivers – and businesses that don’t buy fuel in advance – are all now paying far more than they should be.”
In 2018, the amount of diesel sold in the UK was almost double that of petrol.