Falling oil prices resulted in many motorists paying less than £1 for a litre of petrol for the first time in years, according to a new RAC Fuel Watch report.
As the price of oil dropped to its lowest level for almost seven years in mid-November, the average price of petrol dipped to 106.98p per litre by the end of last month.
Diesel, meanwhile, dropped to its lowest price since December 2009 with motorists typically being charged 109.48p a litre at the nation's pumps.
Some retailers, though, went further, the report says. Asda ran a Black Friday weekend promotion, selling petrol for 99.7p per litre at scores of fuel outlets.
Morrisons, meanwhile, gave shoppers a 7p per litre discount for spending £40 or more on groceries, taking the amount they were asked for on forecourts to below £1 a litre.
Simon Williams, a spokesman for RAC Fuel Watch , says the motoring organisation would like to see the widespread sale of petrol for less than £1 per litre. That, he adds, is dependent on the price of crude oil remaining low for a sustained period of time.
But he says the trend has left motorists enjoying lower fuel prices during the run-up to Christmas than they did 12 months ago.
Mr Williams said: "The lower forecourt prices we're enjoying at the moment are a product of the fall in world crude oil prices, which began in September 2014. After a six-year low of $45 a barrel in early February and two instances of going back up to the $60 level twice briefly since, the price has been consistently below $50 since mid-October, reaching a new six-year low in mid-November.
"As it stands we anticipate a very slight average petrol price reduction in the next two weeks and another 2p a litre coming off diesel, taking the new six-year average low price even lower."
Copyright Press Association 2015. Motoring News articles do not reflect the RAC's views unless clearly stated.