First, supermarket Sainsbury's said it was reducing the price of its diesel by up to 2p a litre from Tuesday.
Motorists spared next autumn's planned fuel duty rise have received more good news.
Then rival Asda also announced a diesel decrease of 2p a litre - also from Tuesday.
Richard Crampton, Sainsbury's head of fuel, said: "We know that fuel is a big part of our customers' budgets and therefore we are pleased to announce this cut."
Asda said drivers filling up at its pumps would pay no more than 139.7p a litre for diesel. It added that its petrol remained at no more than 134.7p a litre.
Andy Peake, Asda's petrol trading director, said: "When we do drop prices, we drop them everywhere, setting a maximum national price cap for our customers meaning they all benefit from our low prices, regardless of where they live and are travelling to this Easter weekend."
The autumn fuel duty rise was scrapped last week by Chancellor George Osborne in his Budget.
RAC technical director David Bizley said: "This is a welcome move by the supermarkets and full credit to them for further reducing the cost following the reduction two weeks ago and just in time for the Easter getaway.
"Cuts like these are certainly appreciated by motorists and their families who have had to endure ever-increasing prices on the forecourts this winter.
"New RAC research has found that more than half (51%) of people admit they have had to cut back spending on essential items such as food and clothes due to the high cost of fuel."