Three major supermarkets have reduced the price of fuel by up to 5p per litre this week.
The cuts - from Morrisons, Tesco and Asda - come as the wholesale cost of oil has fallen since the end of October and the pound has recently strengthened against the dollar
The three retailers dropped the prices of petrol and diesel by 3p/litre on Tuesday, followed by a further reduction of 2p/litre by Morrisons and 1p/litre by Tesco yesterday (17 November).
Motoring body the RAC said retailers should have reduced prices two weeks ago rather than making big headline-grabbing cuts now.
A spokesman said the delay in reducing the cost of petrol and diesel will undermine motorists' trust in fuel retailers, as it could be construed they are taking advantage of drivers in the current climate of rising goods prices.
"A fall in the price of fuel due to a stronger pound is allowing us to pass further savings on to our customers. We will continue to make sure we are as competitive as we can be on price in every one of our petrol stations," said Roger Fogg, Morrisons services director.