Hundreds of supermarket filling stations will be offering cheaper fuel from tomorrow.
Asda led the way today by announcing a 2p cut in petrol and diesel.
Then rival Sainsbury's, followed later by Tesco, said they would be cutting their fuel by "up to 2p a litre" - also from tomorrow.
Asda said its reductions would mean motorists paying no more than 131.7p a litre for petrol and 137.7p a litre for diesel.
Asda petrol trading director Andy Peake said: "Today's move shows that we are once again leading the way in reducing the price at the pump.
"Unlike other retailers, our price cuts benefit everyone across the country, meaning that no one filling up at Asda will be forced to play a postcode lottery."
Sainsbury's head of fuel Richard Crampton said: "With Christmas on the horizon, we know that this can be an expensive time of year so we're delighted to announce that from tomorrow we will be lowering our petrol and diesel prices by up to 2p per litre."
A Tesco spokesman said: "We are dropping the price of unleaded and diesel by up to 2p per litre from tomorrow morning.
"As Britain's biggest petrol retailer with 490 forecourts, more motorists will make savings at the pumps at Tesco than at any other fuel retailer."
RAC technical director David Bizley said: "These price cuts are welcome, but they only solve part of the problem. The price that motorists pay on the forecourt is almost 60% tax, with a recent study showing that a record 81p from every litre of petrol sold now goes to the Treasury in fuel duty and VAT.
"What the British economy desperately needs is fairer-priced fuel on a long-term basis. As a supporter of (campaign group) FairFuelUK, we are lobbying the Government to reduce the amount of tax on petrol and diesel, as we believe this will help to stimulate the economy and generate more income for the Treasury.
"We are calling on the Government to increase transparency and make it a requirement for fuel retailers to print the duty on receipts so that the motorist can clearly see how much of the price is tax, how much is VAT and how much is going to the retailer."