A Christchurch car dealer claims mistakes with emissions data in the Clean Car Scheme have cost him $100,000 and counting.
Others say the problems are skittling some deals for buyers, propelling demand for hybrids - and may add to vehicle prices.
But Waka Kotahi - the New Zealand Transport Agency - says there is no systems-wide problem and few vehicles are affected.
The scheme began on 1 April, applying rebates or nil fees for low emissions, and escalating fees for vehicles as their greenhouse gas emissions rise.
Half a dozen dealers told RNZ they have come across fee and rebate mistakes that ranged from hundreds of dollars up to $3000 per car.
Martin Harcourt of Value Cars Warehouse in central Christchurch relied on the official website Rightcar to identify vehicles in Japan to import that would incur nil emissions fees - basically cars with small petrol engines.
But when it came to registering these cars here, he got a shock: The system tried to charge him a $2300 fee for a Ford Focus, after an independent evaluation came in at zero.
They had a similar experience with Audi A1s and Ford Ecosports.
"We can't do business," Harcourt said.
"It's very hard when you are buying a car in Japan and you think it's a nil fee and then you get it, and go and register it and it's $1500 or $2000.
"It's happening all the time."
Waka Kotahi said it was aware of only 145 vehicles nationwide with incorrect data - and 122 had been sorted - out of almost 10,000 imported this month.
Minister of Transport Michael Wood said Waka Kotahi had provided assurances they were "isolated cases".
But Harcourt said he alone had 100 cars in his yard affected, and estimated thousands of cars nationwide and many dealers were hit.
He faced customers walking away while he tried to get the right emissions data. It had taken 10 days to sort out a Toyota Corolla that showed a $1500 fee, when in fact a $900 rebate actually applied.
"We are losing sales because of it. It's probably cost us $100,000 in misinformation, I would say."
He added he was not against the clean car scheme - but its rollout was a "complete mess".
The auction sheets used by agents in Japan do not include the information that is key to calculate emissions.
Waka Kotahi said it was rectifying isolated problems "on a case-by-case basis".
"However, at the wider system and fleet level there is no system failure," it said in a statement.
Yet others are experiencing impacts.
The chief executive of Autohub, a major shipper of used cars from Japan, Frank Willett, said he knew of deals derailed by fees.
"Occasionally dealers have reluctantly worn a penalty payable, and that's just simply been deducted from the margin of the vehicle sale," Willett said.
"In some cases where the anomaly is significant and runs into thousands of dollars, the dealer may elect to tip the deal over, because frankly, it's not possible for him to wear that cost, and it's unreasonable for him to then go back to the purchaser and try and renegotiate the sale price."
He cited a friend who faced a $2875 fee on an Audi that, when challenged, turned into a $500 rebate.
But these challenges cost: Harcourt is spending $300 a time for a Lower Hutt company SOC NZ to get fresh data on European used imports - car-by-car.
"You'd think that would be a blanket for all those cars ... but each car is an individual."
SOC NZ told RNZ the Ministry of Transport did not grasp the enormity of the task given to Waka Kotahi because vehicle data was very complex, especially for used European cars.
Willett suggested some dealers could face $100,000 in extra costs in a year, due to the data problems.
"That has the potential to really drive prices up on yards for the consumer, because at the end of the day if the dealer is is not prepared to go through and research every single vehicle ... he may elect to actually increase the window price."
Opting for hybrids
Online Motor Group chief executive Paul Carruthers said the uncertainties were altering market behaviour.
"The suppliers that I talk to in Japan who are attending auctions regularly are telling me that everyone in New Zealand has defaulted, by and large, to just going after the safe cars which are the hybrids ... given the sheer ambiguity around what kind of penalties they're going to attract if they buy cars that aren't in that safe zone."
Most hybrids get a rebate.
However, even some hybrid importers have been forced since April 1 to send information on hundreds of cars to NZTA to get the emissions data fixed.
Carruthers said some importers who dealt on credit with Japan might simply walk away if faced by an unexpected fee.
"I'm aware that cars have been abandoned here by importers because the cost turned out to be significantly higher."
Several other dealers expressed nervousness problems might multiply as more imports arrive in coming months.
The car importing and retailing association VIA is advising dealers not to register a car till they knew for sure what fees were faced.
It has also asked the minister of transport for assurances that dealers would be indemnified if they gave customers Waka Kotahi data that turned out to be wrong.
Yet VIA chief executive David Vinsen said the problems were merely "introductory". It was getting emissions queries from Japan for four or five vehicle types a day, and feeding the answers to Waka Kotahi, which Vinsen hoped would be used to update its database.
Waka Kotahi, which has 13 staff in its Clean Vehicles Team, was "continuously" updating the data, Wood said in response to a Parliamentary question.
