From earlier photos I've seen online, the carpark used to be just a dirt road off the side of the highway with tall foliage hiding the cars on both sides.
I believe this was when people used to have all sorts of trouble.
The carpark has since been extended. It's wide, open and the entire car park is in plain view of people driving on the highway.
I'd say this has gone a long way to improving the problem.
We didn't have any problems in Jan 2011, although it was a hire car so the insurance covered us completely anyway.
The old carpark
http://www.retiredaussies.com/ColinsHom ... G_6079.jpgThe new carpark
We left trip intention details at the Queenstown police station. He also told us
Just dont have any valuables in the car and leave the glovebox open and empty.
He also said they'd done a crackdown in the last few years and had caught the Queenstown locals who were causing the majority of the problems.
Good luck!