Labour leader Andrew Little says figures showing it was taking an average of seven months to house people who reported living in cars were "disturbing."
Government figures show in the three months to June it took an average of 217 days to rehouse 35 people or families who reported cars as their accommodation and had applied for housing.
That was an increase from 108 days it took to rehouse 41 people in cars in the three months to December 2015.
The information also showed it took an average of 157 days to rehouse 11 people who reported living in tents or public places in the three months to June - up from 99 days for 17 applicants in the quarter to December 2015.
The figures were for applicants who recorded cars or tents as their accommodation at the time they went on the social housing register but did not mean they had lived in cars or tents for the entire period. It was possible they had moved into emergency housing before a more permanent home was found.
The information was obtained by Little who said it also showed more people who reported living in cars or tents were applying for housing than a year ago.
Numbers on the social housing register who said they were living in cars or tents had increased from 107 in the three months to September 2015 to about 163 in the three months to July.
He said the fact it was taking seven months to rehouse families the Government had claimed were a top priority was "disturbing."
Prime Minister John Key and Social Housing Minister Paula Bennett had "made a song and dance" about providing swift help for the homeless. "In fact the opposite has happened."
Bennett defended her progress on developing social and emergency housing, saying there were 800 emergency housing places in New Zealand and once full motels could be paid for from grants.
"There is absolutely no need for people to remain living in insecure housing."
She said the Government would also soon announce further steps in its social housing programme, including community housing providers to offer more than 1000 homes.
However, she acknowledged there had been "challenges." Those included delays in building because of the time it took to get consents, infrastructure and building work done. There were also "people challenges" such as difficulties contacting people on the housing register.
Of the 1100 offers of housing each month, about 150 had to be withdrawn because Housing NZ could not contact the applicant.
Bennett said there were 3185 community housing places in New Zealand and an increase in state houses in Auckland with a further 3000 in the pipeline over the next three years.