In regards to you frontal impact requirements, you would be far better off asking the compliance workshop, you will get the straight and correct answer from them. I have a shitload of paperwork from them and I can't find an answer to your question in any of it. As for the compliance requirements:
Vehicles which have a registration that has lapsed for a period of 1 year or more, and are first registered in New Zealand after 1st January 1991 require a compliance check
Standard costs: $360 for a passenger car, $395 for 4WD or other large vehicle
Then you have to pay first time registration of course.
Note that this is taken from Waikato Vehicle Compliance, and I have no idea if prices are standard around New Zealand.
Oh, and if your car has been reged in this country before, and was first reged before jan 1 1991, you only have to pay for rego, not for compliancing. If it hasn't been reged, regardless of age it will require compliance - AFAIK this is where the frontal impact laws
might catch you out, it all depends on the car.