WHEN you carry the name Lamborghini there are some things that are expected of you - like driving around in the famous Italian sports car that bears the proud marque that is unmistakeably family. But Tonino Lamborghini, only son of Ferruccio who founded the company and designed the cars, is a practical man. Although he owns a Lamborghini or two (actually he has seven sitting in the carport of his hilltop villa in Bologna, but who's counting!), Tonino drives around in a Rolls-Royce. He explains: ''I only drive a Lamborghini for leisure. But I am working most of the time, and when you are on business you need a car where you can travel with more than two people.'' It is certainly business that brings him to Hongkong to launch his latest line of eyewear - all designed by him, as he admits, ''for a hobby''. And Lamborghini owners in Hongkong - 14 at the last count - have been invited to a special function where they will be given a free pair of Lamborghini sunglasses to go with the car. Although holding doctorates in both political science and engineering, it is the latter that has come very much to the fore in his life. ''Nearly everything I design carries mechanical references,'' he says. ''All the accessories I design, such as key chains, cuff links and tiepins, are elaborations of car parts.'' Multi-millionaire Tonino, who is married with a two-year-old boy and a 10-month-old girl, helped his father run the 46-year-old company until February this year, when Lamborghini Senior died. He has since taken over the reins fully, although with the sports car operation of the family business sold off to US car giant Chrysler, Tonino's energies in the past decade have been concentrated on ''designing products emphasised by the Lamborghini marque''. Halfway through our chat yesterday, Tonino dives into his brief case (Lamborghini, naturally) and produces a booklet outlining the architect's drawings for his pride and joy - the Lamborghini Museum, which is scheduled to open next April in an area of Bologna not far from where his father was born. It will be a monument to the creative forces of father and son, starting with tractors (the cars, believe it or not, came long after) and oil burners and leading to hydraulic equipment and solar panels - not forgetting all that other stuff as well.