No push button start is factory fitted, I'm not sure they're legal.
Although I have heard of Mercs or something like that with the automatic GPS and sonar valet systems, driverless at top speed of 5km/h or something. Might be still prototype?? Haven't heard much about it for a while.
I think Mitch meant push a button on the remote that will allow you to deactivate the immobiliser and then you are able to start the car....the push button went out with the fx holden.