Australia wide it is illegal to have open / consume alcohol in a public place. (Unfortunately, your car is considered to be a public place)
You can also get fined for a knife, in a backpack, in the boot of your car. (personal experience, but got let off for work related usage)
It is also illegal for a taxi driver to pick up anyone that is intoxicated. (You gotta love this double standard when they advertise to taxi it home after a big night rather than drive)
And Pat, I find my pasty white Anglo complexion to be a major benefit when cops see the car, then see me, the leave me be.