I have no idea how representative this article on the build up of new car stocks is, but it sends an obvious message that, unless you really really need to buy a car now, it will pay to wait until the prices start dropping to levels which reflect the amount of unsold inventory. There is no evidence of material discounting in Hong Kong yet.
One of the commentators suggested avoiding cars built in 2009. He/she has a point - if the cars are left sitting outside for a considerable period of time, I would expect that there would be an element of deterioration and, with at least some of the manufacturers in dire financial condition, I would also expect that both maintenance and the ability to stand behind a warranty would be questionable.
I have no serious intention of buying a car, but if I did I would be waiting until we see serious discounting to clear the build up of stocks. In addition I would only buy from a manufacturuer with a solid reputation for reliability and post-sale support (i.e. BMW, Toyota/Lexus, Honda, Mercedes).