I'm the guy who advised Herb to post this thread. Around twenty years ago there was indeed a "one time only" law pertaining to importing cars from europe. I was just a young punk fresh out of college at the time, and did not personally import any cars, but I know of several instances where guys brought in european spec cars under this provision. This was a long time ago, and now that I think about it I believe Dr. Kayak is right about the cars having to be 5 old to qualify.
Here's the story in case anyone wonders how I know this without ever having actually brought in a car myself. Back in the early '80's, my buddy and I owned a couple of DeTomaso Pantera's, we tore down the ZF transaxle out of one of the cars, and couldn't figure out how to get it back together correctly (those things are complicated as h@ll). Anyway, we finally located a guy who knew about ZF transaxles. This fellow was in the exotic car repair & importing business, and we started hanging out in his shop checking out all the cool cars. He performed all of the DOT & EPA mods necessary to certify a european car for use in this country, and Dr. Kayak is right about having to add steel reinforcements to the doors, change the lights, etc. He also had to add smog pumps, EGR, catalytic converters and such to meet EPA regs. After making all the EPA mods, you had to run on an emissions dyno to verify you were clean enough... this guy kenw all sorts of tricks to get the cars to pass! Ferarri Boxers were the most popular car to import back then, even though you could already buy them stateside, the importing, and converting business seemed to be primarily for guys with more money than sense!
This same guy also advised folks on how to bring in cars under the once in a lifetime rule, or what ever it was called. This seemed to confuse the customs types, and just about everyone else, near as I could tell. I remember hearing about cars getting seized and so forth due to ignorance of the rules. Our buddy was always on the phone trying to help customers with all the customs red tape. However, I did see, with my own eyes, euro-spec cars in this guys shop that were imported and registered in this conutry without being converted. Again, Dr. K is probably right about the 5 year old business, so this law, if it's still in effect would not help Herb anyway.
Sorry for the long post, I think this one's a record for me, just wanted to set the record straight.