But of course the car companies have the resources to do all the testing and modifications to import whatever model they deem will sell well enough in the US market. Sure, a 1-off importation of a 17 year old Audi is never going to be economically reasonable, but if Audi wanted to import that model when it was new they certainly would have had no trouble making it meet the requirements. They just didn’t think it would sell well enough to be worth the effort.
Oh, by the way, if the car you want to import is 25+ years old a lot of the requirements get waived and it becomes much easier. Check a back issue of Car & Driver from about a year ago where one of their writers imported an old Australian car of some sort.