I lived in the Unley area, and was on greenhill rd. yesterday about 7ish, and it was quite the sight as all the people going to that cruise drove along Grenhill Rd. towards the hills.
Lots of cars revving their engines hard, to make themselves noticed among the big crowd, even a few 'involuntary wheelspins' were heard and seen by the many unexpected pedestrians.
I wonder how the cruise went in the end, and it there was some issues with the boys in blue, (defect stations and the like)