Direct from California Department of Motor Vehicles..
How do I register a NON-USA or "Grey Market" car in California?
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Vehicles first sold, or vehicles intended for sale by their manufacturers outside the United States are called NON-USA or "Grey Market" cars. Greymarket cars are typically not able to be used or registered in California. The following information lists the minimum requirements to register a greymarket car in California:
If the Model Year of the vehicle is:
1967 and older: no modifications and testing are required to register the vehicle in California.
1968 to 1974: California does not recommend the purchase or importation of these years of NON-USA vehicles, even if currently registered in another state. These vehicles require compliance with USEPA requirements in effect on the specific date of 11/15/1972. This provision when written, was considered by the California legislature as a gradual phase-out of very dirty "non-collectable" types of imports, as this specific requirement was understood to become increasingly difficult to meet. Today, this requirement, while not impossible to meet, would require testing expenses and modifications that far exceed most vehicles value and would make little sense from a collectors standpoint to attempt. Some limited exemptions apply to individuals moving to California with vehicles of these years registered in their home state for at least a year before moving to California. Contact us for more information.