About 200 people braved freezing conditions overnight to sleep in their cars as part of the Park Up for Homes event in Auckland's Onehunga.
Organiser Josephine Bartley said the campaign was about showing solidarity with homeless people, who did not have a choice about where they spent the night.
Many of those who took part had never been to any kind of protest before.
Boxing legend David Tua announced last week he would sleep in his car for the event, joining a growing national movement calling for houses for homeless families.
Tua and his new wife Helen said they had planned to attend the first Park Up For Homes event, which drew 700 people to a Mangere carpark last month, but pulled out because Mrs Tua was unwell.
Park-ups have also happened at Otara and at Parliament in Wellington.
Tua told the Herald he lived in a car himself for six weeks in Florida in 2009 when his American promoter ran out of money.
"The only thing he could afford was to get me a car," he said. "I didn't tell him what I was doing but I actually stayed in it for a month and a half."
The Tuas now run a gym, David Tua Health and Fitness in Onehunga, and said several gym members were homeless.
The couple have supported the Manukau Salvation Army's work with homeless, and Tua was shocked by what he saw.
"I couldn't believe it could happen here in Aotearoa," he said.