Did a little digging and this is roughly what your VIN means.
6G1E = General Motors Australia
K = SV6 (P= SS)
5 = Sedan
E = Control letter
V = (Perhaps colour code?)
4 = Series II (2 = series 1)
b = Year of manufacture - 2011
L = Elizabeth manufacturing plant
578066 = Production number
You could always call or email Holden and they should be able to provide you with the manufacturer details. I did this with Ford for an old Falcon of mine and found out it was an ex unmarked Police car (had the police package installed) from Melbourne and even mentioned the particular station it was sold to. After calling VICPOL transport, they pulled the old files and figured out it was used by the major crimes / detective unit.