There are numerous issues. I would surmise that you have cargo insurance for the transport of the vehicles, but if not you need to get that. You also have various taxes, duties and disclosure requirements under ITAR and other statutes. While a vehicle itself may be relatively harmless, some of the parts can be used for illicit purposes. You will need to contact an attorney well versed in this area of the law. There are many good import/export attorneys here on AVVO, and one of my collagues here in Washington can assist.
The foregoing is not legal advice nor is it in any manner whatsoever meant to create or impute an attorney/client relationship.