No one has any illusions about the time it will take to transform Hong Kong into a clean-air city. It will be a major operation to switch commercial vehicles to liquefied petroleum gas (LPG) and to provide the service stations needed for the new fuel. But the pace of change will be a lot smoother if everyone involved does their best to co-operate. Given the frequency with which the bigger oil companies trumpet their environmental credentials in television commercials, they might have been expected to be among the first to welcome the Government's commitment to cleaner fuel. Of course, it is going to be expensive, with some weighty logistical challenges in locating filling stations suitable for conversion. But a show of willingness would be an encouraging start. These companies, remember, charge more for their products here (before taxes) than almost anywhere else. They have proved impervious to years of criticism from the Consumer Council because the secretive way they work makes it impossible for a non-governmental group to verify their claims of high infrastructure and operating costs. But the fact that they increase pump prices when oil costs rise on world markets, yet less freely lower them when the price of crude oil drops, should give some clue about their business philosophy. In January, when prices rose here due to increased oil costs and worldwide demand, Shell claimed it had to cover losses sustained in the previous six months. If oil companies have been only scraping by locally, would it not make sense to open the books to prove the point? But like several other enterprises in this self-styled free market, these firms are, according to the council, 'an oligopoly' which can do pretty much as it likes in the absence of much competition. So long as the Government refuses to set up a competition authority, local consumers are at the mercy of such businesses, whether they be supermarkets or service stations. A competition subcommittee has recently been set up under the Energy Advisory Committee to monitor oil companies. Here is the committee's opportunity to show what it is made of. If oil companies can show just cause for seeking taxpayers' money for changing to LPG stations, they should get it. If there is merit in their argument that they cannot afford to charge the $2.01 per litre price agreed for the five new sites, granted without land premium, then further negotiations may find a compromise. But sob stories about the plight of shareholders are hard to swallow from companies which reap so many billions year after year.