Used car sales in March plunged 18% on a year ago, as stink bug-infested ships were turned away from New Zealand shores for biosecurity reasons.

New and used car sales dropped 6.6% in February and 4.4% in MarchInfometrics economist Hilary Parker said stricter controls for dealing with car shipments from Japan was likely to continue to slow the supply chain and prompt further weakness in sales.

"The monthly decline was entirely due to fewer registrations of used imports, with stink bugs holding up car shipments from Japan,'' Ms Parker said in a statement.

Total sales were 20,891 new and used cars for March, a decline of almost 12% on a year ago. Brand new sales (9050) were down 2% and imported used car cars down 18.2%, at 11,841 vehicles.


While expecting a near-term decline in sales, Ms Parker said she expected sales of used cars would regain momentum over the coming year.

She noted a recent ANZ-Roy Morgan survey, which showed consumer confidence had risen 5.7% since the end of 2017 and a net 39% of households thought it was a good time to buy major household items.

In March there had been fewer new large car sales, which drove a 2% decline in new car sales, while March sales of new small cars were up 11% from the year before.

The shift in preference from large cars to small would probably be cemented by the latest increases in fuel excise tax, announced last week, on top of proposed regional fuel taxes."Consumers are already shying away from big gas guzzlers in favour of more fuel-efficient options,'' Ms Parker said.

An additional tax of 20c per litre in Auckland and 10c everywhere else would not have an immediate effect on sales, Ms Parker said.

However, the higher fuel costs could influence people's decisions when they next bought a car and could accelerate the removal of older, less fuel-efficient cars from the nationwide fleet, she