Easier said than done. About a week ago I was researching what it would take to import a Mexican or Brazilian Volkswagen Type-2 (Bus/Transporter) to California. Americans are generally restricted from importing cars that are younger than 25 years old, and in California imported cars must receive expensive emissions testing and certification that are much more involved than the normal smog check process (with some exceptions for classic cars).

Importing cars is not a viable option for most Americans.

Easily made illegal. Government will just seize your stuff, stick it in a warehouse, and bill you for it.

If the car doesn't meet USA emission and safety standards, it's already so hard that it may as well be illegal.

https://www.cbp.gov/trade/basic-import-export/importing-car