A Department of Corrections sniffer dog surprised staff during a training exercise - unearthing "a substantial amount of drug paraphernalia, residual methamphetamine and ammunition".
The dog was being run through its paces at a Hamilton car auction yard when it made the discovery.
Corrections Service support manager Scott Carse said the vehicles, seized by the courts or recovered in accidents, are ideal because they are full of things encountered at prison checkpoints like food wrappers and empty bottles, that act as natural distracters for the dogs.
"However, during the exercise all the dogs indicated on a vehicle that hadn't been set up for the training exercise," Mr Carse said.
"This led to a search by the handlers and what was discovered was a substantial amount of drug paraphernalia, residual methamphetamine and ammunition.