I think the issue is that you can get them into the US but if you want to title the car and register it with a DMV for use if it isn't 25 model years old or better it's gonna be no dice baby.
In NY, it is as Ron says, you need a title to transfer or a MLO (manufacturer's letter of origin).
In NYS, I believe that you possibly could register it as a home build car BUT in the past that meant that a Title would be issued stating that AND the STATE of NY would issue a chassis serial number and apply it.
There may be rural states that are less strict but as far as I know even if they are the car still needs to conform to US DOT requirements.
In the past some of the importers had other options.
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