MERCEDES-BENZ, is facing drastically reduced sales in other markets, but Hongkong car buyers still rate the Stuttgart marque above all others. Last year, Mercedes-Benz were again the best-selling European luxury brand in the territory with 2,910 cars sold by the official distributor, and a large number of Mercedes limousines sold by private importers. In fact, the latest S-class Mercedes, declared the best luxury saloon in the world by the motoring press, is almost common in the territory. Contech SLS Restoration Services, in Yuen Long, is gambling that Hongkong car buyers want Mercedes-Benz cars with an extra touch of class and history, and are offering restored classic 1950s and 1960s SL models. Mr Peter Zahalka, the manager of SLS, said: ''If you buy the latest Mercedes for a couple of million dollars, they would not look at you, but people respect nice-looking things of the 1960s.'' SLS was founded about a year ago when Mr Zahalka found his job as service manager for Contech, a construction techniques company, was not fully occupying his skills or his time. With 27 years' experience in automobiles it was hardly surprising that he chose to work with cars. SLS is not just a hobby for Mr Zahalka or a sideline for Contech. He said SLS was the Mercedes restoration specialist Hongkong had lacked. He said: ''We offer the best restoration for the lowest money; we use only Mercedes parts and use no fibre-glass, it is all metal - no one else can offer a service like that.'' The operation is growing rapidly and is gathering both the manpower and equipment to handle any task. Mr Zahalka was confident the company was ready to expand its list of customers. Currently, there are six mechanics in the workshops, two from Scotland, one from England, one from the Isle of Man, one from Vienna and one Chinese. The only thing they all have in common is a high degree of professional skill. In the words of one of the workers: ''We are all good, all trained, and all know what we are doing.'' SLS Contech was taking advantage of the construction arm of its mother company to improve the workshop's facilities. But Mr Zahalka is determined that SLS will continue to offer customers personal service. All cars are listed in files with complete records of work done. The work carried out on each car is impressive and most probably equals the quality of the factory, but the cars that SLS restore are not meant for concourse shows. They are meant to be used on a daily basis and SLS sets out to keep costs reasonable. The labour cost is $300 an hour and planned according to the Mercedes factory allowance for the task. If the book says that it requires three hours for a factory mechanic to remove an engine, then that is the time SLS will charge for the job. A five-year warranty is put on all work done. Contech SLS can be reached on 482 2518.