THERE can be no doubts about the target audience for one advertisement on the Hongkong Football Club's notice board - boy racers. ''Extremely fast and noisy. Goes like the clappers,'' reads the blurb for a bright-red 1970 Triumph TR6 with a 2.5-litre, six-cylinder engine. It went on to say how the body and engine were in excellent condition (are second-hand cars ever in anything but pristine shape?), with the original wood steering wheel and dashboard intact - all for $110,000. And the name of the man selling this four-wheeled sports car - none other than Mr David Nendick. Can this be the same man who recently retired as the Secretary for Monetary Affairs? If so, few would have guessed that under the civil servant's dusty and almost Dickensian appearance there lurked the soul of a speed freak.