I searched and found many articles on importing a car but I still have two questions.
Is a 911 Turbo (996) that was built in GER for the US market going to need major changes to comply with Swiss law? I know it may be a stretch to ask on a specific model but you never know.
Also, if I am reading the law right, I don't have to register it for 1 year? Is that only for EU cars? If you can drive it on US plates up to a year, can you insure it?
do you have km/h and mp/h on your speedo? I know my wife's cayenne doesn't have kp/h on the speedo itself but can show kp/h on the digital display. I know the germans accept this when imported into Germany, but not sure entirely about the swiss.
I would try to find a US car importer and they are able to check the specifics of your car and see what changes you may have to make.
With regards the 1 year. Yes, you are able to drive it on US plates up to a year. The theory being that during this period you make the appropriate changes to your car to be able to register it.
If you do a search, some companies do insure under such circumstances. I do know that in my case Mercury doesn't cover Switzerland so I will have to get insurance locally.