Prices at the pumps across Kent are varying by as much as 8p per litre - and motorists want to know why.
Reports suggest drivers were paying 137.9p per litre at Esso in Deal at the weekend, while at Esso in Canterbury motorists were filling up for just 129.9p per litre.
Campaign group Fair Fuel UK, which started in Kent, is calling for a government inquiry to get to the bottom of the fluctuations in fuel prices.
Howard Cox, of Fair Fuel UK, said: "There is no rhyme or reason prices should vary by almost 10p per litre over a matter of miles.
"We are calling for a full-blown inquiry into fuel pricing in the UK. No one knows who is manipulating the figures. You can look at wholesale prices, but these are also all over the place.
"When there is trouble in the Middle East, prices go up like a rocket and down like a feather. Prices can go up in an hour, and take weeks to come down. We want to know why this is."
Fuel pricing is opaque at best, with a number of different factors in play.
As much as 60% of the price per litre goes to the government in tax, but the other 40% is determined by a number of variables - from the cost of extracting the oil right down to retailers' profit margins.
The picture is further complicated by fuel speculators who store millions of gallons of oil off shore in tankers, ready to sell when the price is right.
Also adding to the uncertainty are supermarkets which sometimes sell fuel as a loss leader – a product sold below cost to persuade consumers to visit the shops where they spend money on profitable products.
Drivers have been enjoying the lowest UK fuel prices since 2011, but this may be set to change.
The AA's latest fuel prices report, which charts UK fuel prices, says unleaded is up 1.1p from 130.5p per litre to 131.6p.
Diesel prices have increased 0.4p from 135.7p per litre to 136.1p.
The increase chimes with a recent warning from Iran's Petroleum Minister Bijan Namdar Zanganeh.
He told the Iranian state news agency the low oil prices of $105 per barrel could not continue "due to seasonal fluctuations" and the increased cost of extraction.
What do you pay to fill up? Have you seen a bigger price variation? Let us know by emailing email@example.com.
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