The plummeting value of the pound could lead to Brits paying £3 more to fill up a tank of petrol or diesel.
The pound suffered further falls this morning, dropping to US $1.06 at one stage after reaching $1.08 yesterday.
And analysis shows that if the pound reaches parity with the US dollar, then the wholesale price per litre of oil will likely increase from 63.5p to around 68p.
This 4.5p rise would result in an extra £3 to fill up an average tank of petrol.
The grim prediction comes despite fuel prices at UK forecourts falling to their lowest level since mid-May, according to figures published on Monday by the Department for Business, Energy and Industrial Strategy.
RAC fuel spokesman Simon Williams told the i, which conducted the research, that a falling pound is "bad news for drivers at the pumps" because wholesale fuel is traded in dollars.
He added: “Fortunately, wholesale petrol and diesel costs have reduced in recent weeks due to the price of oil coming down which has led to lower prices at the pumps, but if oil were to go back up, the weak pound would definitely lead to drivers paying far more to fill up.”
Luke Bosdet, the AA's spokesman on fuel prices, also said: " Petrol prices have crashed in recent weeks from a record of 191.53p in early July, but they should be very much lower now – and this time it’s not the fault of the fuel retailers."
A litre of petrol cost an average of 165.5p on Monday, while diesel was 181.1p per litre.
They are the lowest prices since May 16, coinciding with a fall in wholesale costs due to a drop in oil prices.
The highest average fuel prices for the year so far were recorded on July 4, when petrol was 191.6p per litre and diesel was 199.2p per litre.
Since then, the cost of filling up a typical 55-litre family petrol car has been cut by more than £14, while refuelling diesel models costs nearly £10 less.
Mr Bosdet said: "Although the fall in pump prices has slowed in recent weeks, they continue to trickle down steadily.
"This was to be expected as the end of the US summer motoring season eases the pressure on gasoline demand and therefore reduces the wholesale price of petrol in this country.
"At UK street level, petrol prices around 155p a litre are beginning to appear again."
Despite the fall in prices, a new survey indicates that 50 per cent of UK drivers are cutting back their car usage to save money.
The poll of 2,807 people commissioned by automotive classified advertising business Auto Trader suggested that motorists in north-east England are most likely to be reducing their mileage, at 56 per cent.
Some 68 per cent of respondents from across the UK said they plan to sacrifice eating out in favour of filling up their vehicle.
