Figures from Experian Catalist show the average price of a litre of petrol at UK forecourts – places like BP, Shell and Texaco – reached a record 182.3p on Wednesday, an increase of 1.6p in one day.
For families, this means filling up a 55L car will amount to £100.27 – for a litre of diesel, the average price is 188.1p.
RAC fuel spokesman Simon Williams said the £100 threshold is "thoroughly depressing" and a "truly dark day" for drivers.
He said: "There’s almost certainly going to be upward inflationary pressure, which is bad news for everybody.
"While fuel prices have been setting new records on a daily basis, households up and down the country may never have expected to see the cost of filling an average-sized family car reach three figures."
Mr Williams said many people will be hoping for further financial support from the Government as the 5p per litre cut in fuel duty “looks paltry” – since it was implemented, wholesale petrol costs have increased by five times the amount in March.
“A further duty cut or a temporary reduction in VAT would go a long way towards helping drivers, especially those on lower incomes who have no choice other than to drive,” he added.
Filling the tank started becoming more and more unaffordable during Russia’s invasion of Ukraine, as the cost of oil increased.
It continues to rise due to increased demand for fuel across the world as China eases its Covid restrictions and the US and Europe enter the peak summer driving season.
Supermarket forecourts have proven to be much cheaper than UK forecourts, priced 4p per litre less.
Data from petrolprices.com shows the cheapest place to fill up today:
Applegreen, Church Stretton: Petrol - 170.8p, Diesel - 181.8p
Asda, Southwater Way, Telford: Petrol - 172.7p, Diesel - 181.7p
Asda, Donnington Wood: Petrol - 172.7p, Diesel - 181.7p
Asda, Old Potts Way, Shrewsbury: Petrol - 173.7p, Diesel - 179.7p
Sainsbury's, Colliers Way, Telford: Petrol - 174.9p, Diesel - 183.9p
Sainsbury's, Hereford Road, Shrewsbury: Petrol - 174.9p, Diesel - 179.9p
Morrisons, Whitchurch Road, Shrewsbury: Petrol - 175.7p, Diesel - 181.7p
BP, Beatrice Street, Oswestry: Petrol - 175.9p, Diesel - 187.9p
Motorists are advised to avoid speeding, accelerate and brake less suddenly, and remove excess weight from their vehicle.