Prices can differ by as much as seven pence per litre, or £3.50 on the cost of filling up an average-sized car such as a 50-litre Ford Focus.
On average Winchester drivers are paying 2.5p per litre more than in Eastleigh and Chandler’s Ford.
The differentials are there even for petrol stations of the same companies.
The price of unleaded petrol from a Tesco Esso Express on Andover Road, Winchester, could cost 4p more per litre than the Tesco Esso Express in Twyford Road, Eastleigh, so that filling a 55-litre car with unleaded petrol would cost around £2.20 more each time a driver fills up.
Tim Shallcross, head of technical policy at the Institute of Advanced Motorists, said: “If you talk to fuel companies they may make excuses about the difference in distribution costs, but really, there is no difference in distribution costs between Winchester and a few miles up the road.”
Diesel was on average 3.2p per litre more expensive in Winchester, while the cheapest unleaded petrol was being sold at the Esso and Total garages on Bishopstoke Road, and Tesco Express on Twyford Road — all in Eastleigh — at 130.9p per litre, at the time of our survey.
Professor Neil Marriott, dean of Winchester Business School, said: “It probably reflects the higher costs associated with Winchester house and land prices compared to other areas.
“There may be an element of pricing to what the local market will bear and possible limited local competition.
“Economies of scale are also a factor. Outlets selling more petrol can usually charge lower prices.”
Luke Bosdet, of the AA, said the price difference could be down to what is becoming known as the ‘Asda effect’.
He said its business model allows it to offer low prices at the pumps, making the money back in the aisles of hypermarkets like the one in Chandler’s Ford.
“There are two types of towns in the UK: those with an Asda petrol station and those without.” Mr Bosdet said.
“It’s down to what they call price matching. The supermarkets will price-match the lowest prices in a town, and if you have an Asda in a neighbouring town, that tends to be why prices there are significantly cheaper.
“We’ve also got people helping to pump up the price and it’s the poor old driver who is footing the bill.”
The Shell garage on Easton Lane was charging a penny a litre more than the next nearest Shell in Chandler’s Ford.
A spokesman for Shell said: “We know it is confusing and frustrating for some customers to see prices varying in their local area. There are simple business reasons for these fluctuations. We set the prices at our company-owned sites but not at independently-owned and operated Shell-branded sites. This is why you might see price variation even when sites are close together.”
Tesco declined to comment on why Winchester motorists pay more than those in Eastleigh, but was happy to comment in general terms.
“Our clear goal for customers is to be competitive on petrol and diesel in the local catchment area for each store, so Tesco does not operate with one national price.
“This is the case with all other petrol retailers in the UK,” a spokesman said.
Lesley Rose, social policy lead at Winchester Citizens Advice Bureau, said high fuel prices were having an impact on those with the lowest incomes.
“It’s one of the problems we see. The cost of running a car, with petrol prices included in that, is very difficult indeed for somebody on basic benefits.”
The city’s businesses are feeling the effects of high petrol prices too.
Akeel Khan, owner of Winnall-based Wessex Taxis, said: “Our drivers do feel the impact, very definitely.
“We do school runs, work which is subcontracted out by the council. The council wants us to have more vans so we can take wheelchairs — but that means more diesel and we’re going to have to go back to them and say ‘it’s just getting too expensive’.
“If we have a job in Southampton, the drivers will definitely try to fill up from there, but it can’t always happen.”
But green campaigners argue prices are not high enough.
Chris Gillham, of Winchester Friends of the Earth, said: “I would sympathise more with the taxi drivers of Winchester if I saw them switch their engines off more.
“They do not behave as if the price of fuel is that great. I see them outside my house and they’re happy to leave the engine running while they wait for people.
“It’s a great pity that the government has come off the fuel price escalator. Fuel ought to be a lot more than it is.
“There’s always a complaint about the price of petrol, but in terms of real costs of motoring, motoring is highly subsidised.
“It’s one of these lovely myths that the motorist is being hard done by — he’s not. He’s being subsidised.”