The average price of a litre of unleaded petrol has dropped back below €1, according to the Automobile Association.
However, at 98.6 cent, it is still running 11 per cent ahead of the average price for this time last year.
In an end-of-year report on petrol prices, the AA said drivers should make shopping around for value a new year's resolution, given the different prices quoted by competing outlets.
A straw poll by The Irish Times of service stations around the country showed a disparity of at least 8 cent a litre.
The AA said the average price for unleaded petrol was 102.1 cent per litre last month, and 99.3 cent for diesel. The former had since fallen by 3.5 cent a litre, and the latter by 2.8 cent a litre.
Mr Conor Faughnan, the association's public affairs manager said: "This is welcome relief for motorists. Prices have risen relentlessly all through the year.
"They remain far higher than they were in January - 90.6 cent - but at least they have come down somewhat and they seem to be set to fall again.
"Although price movements are often down to world events over which we have no control, the ordinary motorist can save a lot of money just by shopping around," he added.
"On our monthly survey, prices vary by as much as 6 or 7 cent above or below the average. Motorist should become a lot more price fussy. "There is just no reason for paying any more for petrol than you need to, and even a few cent adds up to a lot of money in a year's motoring.
"We would encourage all motorists to make a new year's resolution to shop around every time they fill the tank. The more of us who do that the better the competition will become."
He said a motorist who saved 5 cent per litre by shopping around would save €90 on their annual fuel bill. This figure is based on the motorist doing 12,000 miles a year in a car achieving 30 miles per gallon.
This month's fall in domestic petrol prices coincides with a drop in the international price of oil from a $50 a barrel peak.
This is partly due to curtailed demand in the US thanks to an unusually mild winter there.
