Asda has increased fuel prices by an "unheard of" 5p in a single day, as drivers face paying £100 to fill up the average car.
The average litre of petrol cost is now 180.73p and for diesel it is 186.57p, according to latest RAC figures.
This means it currently costs around £99.40 to fill up a 55-litre petrol car and £102.61 for diesel.
Petrol has risen in price by more than 20% since the start of the year, and diesel around 24%.
The soaring cost of driving is becoming a national crisis, according to the RAC motoring organisation.
The average cost of filling a standard family car with petrol could soon top £100 for the first time.
It currently costs £96.50 to buy a full 55-litre tank of petrol, and £101.90 for diesel.
RAC fuel spokesman Simon Williams called the looming £100 tipping point for petrol "an unfortunate landmark".
He added: "Asda hiked its average petrol price nearly 5p a litre in a single day, which is unheard of.
“These are unprecedented times in terms of the accelerating cost of forecourt fuel.”
He added that “we are still some way from the peak” as this will take several days for an unexpected fall in wholesale costs.
An Asda spokesperson said: "The wholesale price of fuel has increased at an unprecedented rate, rising by over 9ppl in the last week.
"Motorists trust us to provide the best value at the pumps and we will do all we can to minimise the impact of rising wholesale prices on our customers."
Why are petrol and diesel prices so high?
Simply, oil prices are rising because it is more in demand and this has been made worse by the war in Ukraine.
There were already shortages that sent fuel skyrocketing last year and now businesses are cutting off ties to Russian oil.
This means that the current crisis could well get worse - and more expensive.
The UK only gets around 6-8% of its crude oil from Russia and a 2020 Autocar report estimates around 18% of UK diesel is from the country.
This is not the same for much of Europe - around half of the barrels of oil Russia produces every day goes to the continent, with the country the world's third-biggest supplier of oil.
The UK is hoping to totally phase out the use of Russian oil by the end of 2022. The EU is far more reliant on oil and has so far committed to drop its usage by around two-thirds.
With countries turning away from Russian oil, there is demand for it elsewhere, which pushes the prices up.
Labour has spoken out about high fuel costs and called for a 'windfall tax' on fuel giants to help hard-up Brits.
Labour's shadow secretary of state for transport Louise Haigh has said: "Working people are facing a cost of living crisis, and the Conservatives have literally nothing to offer.
"Labour's plan would help households through this crisis with up to £600 cut off energy bills, funded by one-off windfall tax on the oil and gas giants taking working people for a ride at the petrol pump.
"The Conservative government needs to set out an emergency budget to tackle its cost of living crisis - and support Labour's call to put money back in the pockets of working people."
