But Perry Kerr, chief executive of the Motor Industry Association which represents new vehicle importers, said new imports would cost no more.
They were already meeting international emissions standards and had been for several years, meaning cars arriving here were already equipped with the required exhaust emission technology.
"A model cycle is about four years, so over a four-year period you're getting the complete change in terms of the vehicles that are entering the fleet - it's been progressive.
"Basically if they know the standard is going to change in two years, they'll build that in when the model is released so they don't have to make a technology change.''
Imported Motor Vehicle Industry Association chief executive David Vinsen said consumers would not notice an increase in prices to used imports either.
"There is no increased cost, there's no change in process, there's no disruption whatsoever, in fact this change will be implemented unnoticed by the trade or the public.''
Mr Vinsen said Associate Transport Minister Simon Bridges was clarifying the rules for the industry.
Vehicles are required to go through a compliance process requiring documentary proof they meet vehicle exhaust emission standards. That proof would come from the manufacturer or from other sources.
The vehicle has to meet a physically tail pipe exhaust emission test in addition to this.
"It's not an either or situation, it's a both - it's always been the case but there's been some confusion about it. All this amendment does is remove all doubt,' Mr Vinsen said.
Manager of the Infinity Cars car dealership on the North Shore, Beshar Qastom, said he was not aware used cars were required to have documentation saying they met exhaust emission standards.
