Father Steve quoted from my website (http://ozlip.lexigame.com/ozdict.html#hoon), about hoon, but let me expand on that.

Australian dictionaries give a few meanings for hoon, apart from the reckless driver. The oldest sense seems to be a procurer of prostitutes. This meaning is labelled "dated" by the Australian Oxford. (Another Australian slang term, "bludger", has a similar original meaning, but now usually means a cadger , or parasite of any kind.)

Other meanings for hoon given by G A Wilkes in his Dictionary of Australian Colloquialisms are "general term of insult", "anyone given to loutish behaviour" and "a thug, a heavy (not criminal)", as in "security hoon".

It probably is true that the most commonly used meaning now is "someone driving fast and aggressively". "Hooning around" is also used for such behaviour - Wilkes quotes a newspaper article about "rogue jet ski riders" who were "hooning around inside the flags at patrolled swimming beaches".

I have not seen any explanation of the origin of the word.