Has anyone given thought to whether a car can be registered simultaneously in more than one European country (leaving aside whether Swiss norms are compatible with those of any other country).
I once had an estate car registered as a commercial vehicle in New York and as a passenger car in New Jersey. Not totally unusual, and once when my car (a different one) was struck from behind by what turned out to be an unmarked police car, I recognised instantly that it might be that because it had valid inspection stickers (i.e. MOT) from both NY and NJ. (I ran into the same guy a few minutes later at the NY Police Property Clerk's office where I had some business so his cover was blown anyway.)
North American tractor trailers (articulated lorries) are often registered in more than one state because of tax obligations.
As for private vehicles, there are retired people who live out of their Winnebago campers and have no permanent address at all. They tend to register the RV and get driving licenses from wherever they can find someone who will lend them an address.
In Europe the insurance issue might be insurmountable. I know that insurers who cover US Forces in Europe do not restrict movement of an insured vehicle. But I've seen lots of complaints by British motorists that they can't easily get extended Continental cover.
Here's a fact situation: Under the Rush Portuguesa case of the ECJ http://www.biicl.org/files/1957_c-113-89.pdf
a non-EU/EEA/Swiss citizen (i.e. a third-country national) can be assigned by an employer to work in another EU country for up to a year. What about that employee's car, after 6 months?