Rural motorists are beginning to feel petrol price pressure at the pumps again, according to the Hampshire-based AA.
Average UK petrol prices went back above 130p a litre at the end of April and continue to hover around that level.
But the AA, based in Basingstoke, said that a war in which supermarkets have pitted vouchers against rock-bottom pump prices means the cheapest petrol in many big towns and cities is at year-lows of just under 126p.
It added that in small rural towns, where major supermarket competition was less fierce, the price gap between them and cheaper major towns has started to grow again to 4p a litre.
AA president Edmund King said: "While supermarkets, faced recently with worse sales figures when fuel is factored in, have held their fire on pump price increases in cities and major towns, there are signs that some of them and other retailers are getting price-trigger-happy again in rural towns.
"A 2p increase in the wholesale price of petrol through March into April may justify that but, if pump prices stay higher while costs continue to fall back, rural drivers will be tempted to look elsewhere for cheaper fuel."
Petrol prices could fall by another 3p over the next two to three weeks, the Basingstoke-based AA said today.
The average price of petrol now stands at 136.89p a litre following supermarket cuts, already 3.02p lower than a month ago.
The AA said average petrol prices could fall to about 134p a litre soon with wholesale fuel prices falling.
Average diesel prices have fallen 4.62p to a current 141.76p a litre, AA president Edmund King said: "The last 12 months have shown pump price volatility is more acute than ever, driven largely by speculation."
Supermarket giant Sainsbury's has announced it will reduce its forecourt prices by 3p a litre.
The cut will come into force tomorrow at all of the store's 266 petrol stations across the country, and also covers diesel. Last week the AA said that UK petrol prices had fallen 4p and diesel by more than 3.5p in the past month.
Asda, Tesco and Morrisons have all announced price cuts in recent weeks.