Supermarkets have announced fuel price cuts for the second time in eight days amid a fall in wholesale costs.
Asda, Morrisons and Sainsbury's will reduce their prices by 4p per litre for diesel and 2p per litre for petrol in the coming days.
This comes after the trio reduced the price of both fuels by 3p per litre on February 5.
But motoring organisations claimed it has taken supermarkets too long to pass on wholesale cost reductions.
Government figures published on Tuesday show average fuel prices at UK forecourts stood at 125.85p per litre for petrol and 131.48p per litre for diesel.
AA fuel price spokesman Luke Bosdet said less than 2p of a recent 5p per litre fall in diesel wholesale costs had been passed on by retailers before the latest price cuts were announced.
He went on: "For those craftsmen, rural workers and small businesses who rely on this workhorse fuel, hiked pump prices deny them the chance to offset other rising costs that leave them struggling."
RAC fuel spokesman Simon Williams criticised supermarkets for the time it has taken them to pass on savings from "weeks of falling wholesale costs".
He added: "The cost retailers have been paying to buy in petrol and diesel, and the price they charge at the pumps, have been severely out of kilter for weeks.
"In fact, we had a bizarre and desperately unfair situation where the supermarkets were putting up prices when wholesale costs were falling, meaning drivers were paying far more to fill up than they should have been."
Mr Williams urged retailers to move away from "headline-grabbing cuts" and switch to daily price reductions.
Drivers filling up at Asda - the first supermarket on Wednesday to announce it was cutting prices - will pay no more than 120.7p per litre for diesel and 118.7p per litre for petrol.
The firm's senior fuel buyer Dave Tyrer said: "We will continue to put the savings straight back into drivers' pockets without any vouchering requirements meaning all our customers, regardless of their budget, will benefit from a price cut at the pumps."