The damage, which amounted to several hundred dollars, was discovered when Gilmour Motors staff arrived at the Princes St premises yesterday morning.
The incident had been recorded on the yard's security cameras.
"It is hard enough without this sort of nonsense happening," Gilmour Motors owner-operator Alistair Gilmour said.
"It is just a pity we have to have security cameras to protect us from this sort of thing."
Three Mercedes badges were prized off vehicles and an aerial was removed from a Honda CRV and used to smear faeces over one of the Mercedes.
A wing mirror from a Chrysler PT Cruiser was also removed.
Salesman Tony Morgan said the damage was some of the worst he had seen.
"This is just mindless."
Constable Amie Manning, of Dunedin, said police were reviewing footage of the incident which occurred about midnight.
Police were looking for a tall, slim, possibly Caucasian male who was wearing a blue hoodie.
He is believed to be in his late teens to early 20s.
