WHILE designers and engineers continue to develop cars that cause less ecological damage, industry specialists say maintenance is the most cost-effective method of containing pollution caused by motor vehicles. ''One of our initiatives involves a commitment to reducing exhaust emissions and this is reflected in our programmes to encourage car owners to have regular check ups for their vehicles,'' said William Tsui, managing director of Crown Motors. ''Maintenance is the easiest, most effective and most cost-efficient way of keeping a car at its best with respect to its impact on the environment.'' Mr Tsui said once motorists discovered how easy it was to reduce pollution through regular servicing, they became more supportive of programmes that encouraged that. Maintenance not only kept a vehicle in good running condition, it made financial sense. Crown Motors had a large customer base, but many other vehicle owners in Hong Kong would be unable to participate in the environment month. Mr Tsui hoped other distributors would launch their own campaigns to involve car owners. ''We hope our sponsorship of this and other programmes will be an example for other companies and individuals to act more responsibly towards the environment,'' said Mr Tsui. The firm's commitment goes well beyond one set of programmes. More schemes are planned on a regular basis. ''We want to continue to do our part to improve the air quality in Hong Kong,'' said Mr Tsui. ''This involves generating a commitment among drivers to having a 'green' car.'' Toyota Motor Corporation itself has drafted a Global Environment Charter outlining the company's worldwide environmental policies and activities. ''As a Toyota distributor, we are committed to adhering to the principles of this charter by giving top priority to environmental concerns,'' Mr Tsui said. ''Among other things, this involves conserving and recycling resources and co-operating with our suppliers to ensure that we give due consideration to environmental issues.''