To import any car older than 25 years — such as the R32 Skyline GT-R — it must get a clearance from the National Highway Traffic Safety Administration (NHTSA). The NHTSA lists eligible models itself, so that is the easy part, and you can get these cars easily in 48 of the 50 U.S. states, except Hawaii and California. Besides, to import a classic or vintage car that you can drive around in the U.S., it must be vetted by the Environmental Protection Agency (EPA). As per MotorTrend, the EPA rules that any car to be imported must be at least 21 years old and unmodified, which means it should be free of any upgrades such as turbo engines.
If you are in one of the two states mentioned above, there are some regulatory challenges. First, you must get California’s Air Resource Board (CARB) clearance. Any imported cars built after 1975 must be taken to a lab for rigorous emissions testing, and every visit costs at least $1,500. You will be required to get a state-approved referee who will help you find a specific lab for the testing. If you fail, you will have to pay an additional $1,500 for another visit.