The Office of Fair Trading announced its probe into petrol price rises on the very day this week that Dallas – the fictional saga of Ewing Oil, now Ewing Energies – returned to UK television screens.

Five years ago the average price of a litre of petrol was 93.3p. Since September 2007, the price has shot up by between 43p and 50p.

Earlier this week, the average cost of a litre of unleaded petrol was 138.9p. A litre of diesel was 143.5p. Prices fluctuate by a few pence for reasons not clear to motorists looking round for the best deal.

Unlike petrol retail companies, supermarkets tend to use petrol as a loss leader to attract customers, buying it on the spot market where uncontracted oil surpluses are sold for whatever price buyers are willing to pay.

Arguably, the fluctuating price of petrol has more to do with the shortage of global storage and refining capacity, rather than the amount of crude oil underground.

A combination of complex factors especially in Europe and the UK including taxation, the increasing preference for diesel and green measures connected with climate-change policies, has led to oil companies cutting costs by rationalisation – reducing storage capacity and not investing in new refineries.

According to the-price-of-fuel website: “in order to be more efficient, oil companies operate with lower stocks than in the past, and this means that if there are supply interruptions there will be more effect on oil prices as there is not a huge back-up supply.”

From 2000 to 2010, refining capacity in Europe and the United States reportedly fell by two per cent and four per cent respectively. Over the same period, China’s refining capacity rose by five per cent. India and the Middle East saw rises of below two per cent.

Under European Union law, the UK, like the other 26 member states, is not permitted to have its own national policy on these important energy matters.

Whether there’s a glut of supply or a bottleneck, oil companies have got the consumer over a 50-gallon barrel. Government benefits too, raking off nearly 80p in duty and VAT from the price of a litre of petrol and more than 80p for a litre of diesel – 20p to 30p more than the cost manufacture, supply and retail combined.

Fuel price rises appear to be market-driven; but sceptics believe there is a deliberate strategy more devious than anything J R could devise in Dallas, tantamount to a covert war on motorists, with ever-higher prices forcing consumption down and thereby reducing emissions.

T&A environment columnist Keith Thomson more or less admitted that this ploy was necessary.

He said: “The future will mean high fuel prices for a number of reasons and we need to get used to it. The cost of extraction in deep, cold water raises the price of crude.

“Relatively high taxation, though not the highest in Europe, allows the Government to keep other tax rates low. A reduction in fuel tax rates could mean an increase in income tax.

“There is evidence that the current price is changing driving habits – motorway speeds are lower and fewer miles are covered. Similarly smaller cars with more efficient engines are selling well. This needs encouraging.

“CO2 emissions from road transport are slowing, though still increasing, and this is encouraged by high crude oil prices and taxation. The increase is due to greater levels of car ownership, and the abuse of cars, for example on the school run.

“Comparisons with other countries are not really valid, particularly in Asia, where car ownership is very low. (USA 85 per cent; UK 56 per cent; China nine per cent; India four per cent).”

But Shipley Conservative MP Philip Davies, formerly a senior marketing manager with Asda, said: “The reason why the cost of fuel is so high is that successive governments tax it to the hilt. It’s an easy way for the Treasury to collect revenue.

“Supermarkets can sell petrol as a loss leader. They can also sell it at a no-profit margin because they have 40,000 other items in their stores to make money on. A petrol retailer can’t do that.

“I have the highest hopes that the new Environment Secretary Owen Patterson will bring commonsense into the environmental debate, and keep the consumer in mind as well.”