The New Zealand Transport Agency says it suspects more than 1000 cars are falsely registered as ambulances as owners try to save some cash - but that drivers risk big fines and no insurance payouts in a crash.
Thanks to an ACC levy exemption for ambulances it costs only $52 a year to register a non-commercial ambulance, compared with $280 for a car.
The difference is even greater for commercial vehicles, which cost up to $590 to register.
Transport Agency spokesperson Andy Knackstedt said there were more than three million licensed vehicles in New Zealand so it was not a big problem, but people who deliberately licensed their vehicle incorrectly were cheating the system.
"These people are effectively ripping off ACC, which means they're ripping off you and I and everyone else who does the right thing and who pays their ACC levies, which are there and which are in place to cover the costs of rehabilitation if you're involved in a crash."
Mr Knackstedt said people could face a fine of up to $1000 if they are found to have falsely licenced a vehicle.