The short version
Entry certification rather than an age rule
New Zealand imports large numbers of used Japanese vehicles and the system is built around entry certification and standards compliance rather than a fixed age cut-off.
Entry certification
An imported vehicle must pass entry certification before it can be registered for road use.
Standards compliance
The vehicle must meet applicable safety standards; some requirements are applied differently to older vehicles.
Established Japanese import trade
Because used Japanese imports are routine in New Zealand, the supporting inspection and compliance industry is mature.
Condition matters more than age
Corrosion and structural condition are central to certification outcomes.
Who decides
Waka Kotahi NZ Transport Agency.
This page is a plain-language summary for orientation. It is not legal or customs advice, and it can go out of date. The authorities named above are the only reliable source for your own situation.