While all fuel prices have risen over the last year, none have leaped skywards with more enthusiasm than diesel prices. The average price of diesel reached 132.7 pence per litre at the end of June – a whopping 22.5% higher than at the beginning of 2008.

The reason for this is that only a certain percentage of crude oil can be refined into diesel – and in the European market, demand has grown so that pretty much all available diesel is being used. One of the reasons for this, of course, is the surge in popularity of diesel cars in recent years.

While lorry, bus and van operators have little choice but to choose diesel vehicles, it’s only over the last 3-5 years that diesel has achieved such remarkable popularity as a fuel for cars. Modern common-rail diesel engines offer strong performance and excellent fuel economy – meaning that despite a purchase price premium, many car owners have made the change.

Sentiment in the industry now seems to be suggesting that this trend might be about to reverse, however. The cost of diesel fuel is so much higher than petrol that only true high-mileage car drivers will save money by driving diesels. In addition, diesel cars typically still cost more to buy and maintain than their petrol counterparts – meaning that for many car owners, they simply don’t make financial sense anymore.

This could be good news for companies such as Audi, who have continued to develop new petrol engines offering reduced emissions and improved performance. Such engines are an obvious replacement for turbo-diesels, as are hybrids. These, however, are still more expensive than regular petrol-engined cars to buy.