Oil prices have fallen by 30 per cent since early December, with Brent crude sinking to 30 US dollars a barrel earlier this week.
Many analysts are predicting it could tumble even further, with Standard Chartered warning that $10 a barrel is a possibility.
The RAC said this could lead to UK motorists paying just 86p per litre (ppl) for fuel, as long as the pound does not continue to weaken against the dollar.
In December major supermarket fuel retailers cut petrol to under £1 per litre for the first time since 2009 – excluding promotions – while diesel was given the same treatment last week. Average prices across the country are 102.5ppl for petrol and 103.2ppl for diesel.
RAC fuel spokesman Simon Williams said: “With no apparent end in sight to the free-falling price of oil, motorists can expect some really low fuel prices in 2016.
“Breaking through the pound a litre price point for both petrol and diesel was clearly a welcome landmark, but it looks as though there is more to come.”