There is no big car show in HK BUT if you want to see Japanese MODELs that never exported officially GO to the old Airport (aparture section) in Kowloon City. There is a quite big second hand or grey market(unofficially import) brand new cars show. You may see some very exciting japanese models which are never exported officially except HK e.g. Nissan Skyline GTR, Nissan President (genuine Nissan top luxurious sedan), Nissan Gloria, Toyota Century (5.0 V12 lux.top model), Toyota Aristo (3.0 twin turbo), Mazda New 929 and there is a individual shop selling super cars like Maserati 3200GT, Ferrari 360, F355 and Lamborghini Diablo...etc
hopes you enjoy it!!