Serious savings for savvy drivers when it comes to re-registering.

The AA and Consumer NZ are urging motorists not to register their cars past July - that's when ACC levies come down.

Consumer NZ head of testing Paul Smith says the savings will depend on a car's safety rating - but they're well worth it.

"The minimum for the least safe vehicles will be about $42 a year, and for the most safe about $132 a year. Mine actually comes up on the 26th of June, I'm just going to renew it for a month then, and 12 months after that."

Paul Smith says it's possible for motorists to specify July as the end date of their next registration.