The average cost of filling a typical family car could exceed £100 as soon as Thursday, the RAC warns.
However, motoring groups have raised concerns retailers are not passing on the cut to customers.
It comes after a government source told the BBC a plan to name and shame petrol stations that fail to do so is "still in the works". But he said while the average price of diesel is heading towards £2 a litre, the cost of wholesale petrol had unexpectedly dropped by about 5p a litre on Tuesday, which if sustained, could stem the flow of "daily record petrol prices".
In response, Asda said wholesale fuel prices had increased "at an unprecedented rate" and "we will do all we can to minimise the impact of rising wholesale prices on our customers". The AA motoring group said the 2p litre rise was a "huge shock", but said the speculation that petrol prices could rise to £2 per litre on average "just gives the fuel trade licence to pile on extra cost and the misery".
Changes in prices at the pump are mainly determined by crude oil prices and the dollar exchange rate, because crude oil is traded in dollars.