New rules taking effect this weekend will stop the public gaining access to personal details from the Motor Vehicle Register.
The law currently allows anyone to pay a fee to get a vehicle owner's name and address from the register by providing the registration plate number.
From Sunday, significant restrictions will be introduced; ongoing access will primarily be for enforcing the law, and the motor industry will have only limited access.
Transport Agency spokesperson Andy Knackstedt says there have been problems with personal information being used in a way that was never intended.
That includes bulk information requests from direct marketers and people getting details to harass, stalk or steal from people.