can a non-resident keep a car permanently in the country?

Even if you are a resident, in my experience, it's not easy. At all.

Esp. coming from the USA.

Unless your car is super rare, would sell it back home and pick up its equivalent here.

BTDT.

Even drove it one year on US plates.

It was certainly worth it.

Tom

P.S. 36 years later I still have it.

Can you? Canton Valais says Yes , provided certain requirements are met. This should apply to all cantons likewise.

Yeah, I didn't take a position on worthiness as s/he didn't specify what kind of car is it. I don't regret doing it for 1 of my cars and expect I'll be in a similar position with it decades from now. The other car was probably more trouble than it was worth.

Things may have changed over the years. For example I bought the border insurance ($$$$) so I could drive on the US plates, but 5 months later a cop pulled me over, told me that's only for european plates and it'd be impounded it if I drove it without completing the registration. YMMV

in case you are a Swiss resident you would have the possibility to have double plates. The second car is then abroad and when you travel you just bring the plates with you.

Its the opposite of the original idea. may work for some