The government is considering law changes that will pave the way for private warrant of fitness (WOF) inspectors to pull over vehicles, says Associate Transport Minister Simon Bridges.
Mr Bridges told TV3's The Nation that under new reforms cars would only need a WOF annually rather than every six months.
"Randomised" roadside checks could also be carried out by private companies, contracted by the government, to check the safety of cars. Currently, only police can conduct roadside checks.
Annual rather than six monthly WOF checks would increase road safety, if accompanied by more roadside checks, which was a smarter way to do it, he said.
But Dogandlemon.com editor Clive Matthew-Wilson says the government's WOF changes are part of a larger plan to let commercial vehicle fleet operators issue their own in-house safety certificates.
"It is alarming to think that rent-a-cops on low wages could start pulling over perfectly legal vehicles which already have warrants of fitness," he said.
The changes were not about saving motorists time and money, but were being driven by commercial operators, who want to eliminate independent safety inspections and save money, he said.
The Ministry of Transport's discussion paper on the changes says larger trucking businesses may be well placed to self-certify their WOFs.
"The public should be very afraid," Mr Matthew-Wilson said.
"Trucks make up only 2.5 per cent of the vehicle fleet but cause 15 per cent of all road deaths.
"As far as the commercial fleet operators are concerned, deregulation simply means more profits.
"As far as the public is concerned, deregulation often means disaster."
The government's figure of motorists saving up to $245 million a year through WOF reforms would only happen if regular WOFs were abolished entirely, he said.