An individual can basically film anything they want (video only, not sound) provided they aren’t breaking any other laws – and bear in mind that there is no “right” to privacy under Australian law.
To put it another way, if I stand on the street and film the inside of your home, I am not breaking any law (provided I’m not doing it for some salacious, Peeping Tom purposes). But if I stand in your garden and do it, I’m trespassing.
Likewise, if I stand on my balcony and film my car – or yours, for that matter – I am breaking no laws.
A camera on your window sill filming your car might be in breach of common property by-laws (the window is probably common property) and a dummy camera fixed to, say, a balcony ceiling would be potentially illegal for the same reason – not because they are cameras (fake or otherwise) but because they have been attached to common property without permission.
But if you put a camera on a tripod and trained it on your car, no one could have any complaints (apart from Mr Jenkins in the ground floor unit who likes to sunbathe naked).
And be careful of fake cameras. If someone thought they were safe because there was a camera trained on them (in a lift, say) but it turned out to be a dummy and an assailant knew that, the person who installed the fake camera could be partially liable for damages.
Also, different rules apply to corporations but I think of your strata scheme has a turnover of less than $3 million a year (someone please correct me if I’m wrong) then privacy restrictions don’t apply.