Wow, I couldn't find squat about the special registrations online. But I did find this:
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http://www.nj.gov/mvc/cleanair/exempt_inspection.html
Vehicles Exempt from Inspection
Inspections are not required for certain vehicles, such as historic and collector vehicles.
Historic Vehicles
To be designated as a "historic vehicle," the owner must ensure that the vehicle
* is at least 25 years old,
* is used only for exhibition purposes or was manufactured before 1945,
* has a special registration and a QQ plate displayed on the rear of the vehicle.
Collector Vehicles
For a vehicle to be designated as a "collector vehicle," the owner must apply* at the time of registration or renewal for this designation and must provide evidence that the vehicle
* is not registered as a "historic vehicle," under N.J.S.A. 39:3-27.3 et seq., or a "street rod," under N.J.S.A. 39:3-27.27,
* is not driven more than 3,000 miles per year,
* is insured as a limited use "collector vehicle." (Proof must be supplied at time of odometer verification.)
For inspection-exempt status, the vehicle must be taken to a state inspection station for odometer and insurance verification.
* Visit the exit end of the inspection station within 90 days of purchasing a collector vehicle.
* Ask the inspector to verify the odometer reading of the "collector vehicle"; MVC may require that the vehicle be equipped with an odometer lock.
* Pay fee ($25 and $10 per renewal) for the special decal which indicates that the vehicle is exempt from safety and emission inspection.
*Call MVC at 609.292.6500 or (toll-free in NJ) 888.486.3339 for an application. Submit the completed application to any MVC agency or by mail to
Motor Vehicle Commission
Collector Vehicle
P.O. Box 016
Trenton, NJ 08666-0016
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They never told me about the inspection w/i 90 days; I've never seen a QQ plated car with any kind of sticker.