We brought in around thirty cars in the mid eighties and learned a lot getting them to pash the FTP Federal Test Procedure.
The whole process stopped for two reasons: #1 the dollar to mark rate changed drastically and #2 the EPA changed their minds (with great proding from the manufacturers). It seemed that allowing a car to pass for just one test was an advantage over what the manufacturers had to do (build a system with min failure rates for 50k miles).
The new rules state that a importer (now classified as a manufacturer) must do a version study and certify cars by class. This pretty much filled what was left of the industry as there is no way to do this for just one car. There may still be someone doing it as I have seen some late model euro cars. I sure would advise against it. The cars have little or no value here, often can't be insured and a dealer won't talk about a trade. They can't be sold at (most)auctions.
Owner 24 bay BSC
Bosch Master, ASE master L1
26 years MB technician