Dunedin's mayor and city MP Pete Hodgson want the controversial Undie 500 rally out of Dunedin for good.
The rally once more descended into chaos last night, with Dunedin police forced to wear riot gear and use pepper spray to disperse student mobs.
About 20 were arrested after more than 600 people pelted officers with bottles, bricks and bicycle parts in the student stronghold of North Dunedin.
The 70 officers took about two hours to disperse the students.
The annual Undie 500 event, organised by Canterbury University engineering students, involves a pub crawl from Christchurch to Dunedin, in cars worth under $500. This is the third consecutive year the rally has led to disorder.
Hodgson, who represents Dunedin North, told Radio New Zealand it's time to put a stop to the event.
Mayor Peter Chin said the Undie 500 isn't welcome in Dunedin, and suggested the Canterbury students trash their own city instead, RNZ reported.
The event has previously caused headaches for Dunedin police left to control riotous behaviour at the end of the trip.
Last year's official Undie 500 was cancelled after rioting in the city resulted in 69 arrests the previous year.
However, an unofficial version of the event still ran and 30 arrests were made after another round of disorder.
Most of last night's action centred in the three blocks around Castle Street, with mobs setting furniture and piles of rubbish on fire in Castle and Leith streets, Dunedin Area Commander Inspector Dave Campbell said.
One officer was hit in the head and knocked down with a hurled bottle, and would have been seriously injured if not for his helmet, he said.
Flying bottles hit two or three other people, who had to be taken away by ambulance for treatment.
Mr Campbell said there would be a boosted police presence this weekend and anyone arrested would gain a criminal record, due to a no-diversion policy.
"We're encouraging those involved to enjoy themselves within the bounds of the law," he said.
Most of those arrested were Otago University students, Mr Campbell said.
They faced a variety of charges, ranging from disorderly behaviour and breaching the liquor ban to wilfully setting fire to property.
The officer in charge of the police response, Inspector Alistair Dickie, said they had chosen to take a softer approach this year and were relatively pleased with how things turned out last night.
"We are happy we have been able to stabilise the crowd without exerting our authority too much," he told the Otago Daily Times.
"We could have sparked something here. We are pleased at the moment. Hopefully, I don't eat my words."
- Stuff.co.nz and NZPA