Yes, you simply can. That’s the truth.
Nobody said ‘forever and ever’, the comment made was that no Canadian could drive a US plated vehicle into Canada and that simply is not true. It can stay a maximum of 6 months plus one day before it needs to cross the border again. No different than a Canadian plated vehicle entering the US.
Are there restrictions, yessir. Is it “no how no way”, not it’s not.
I have been bringing my FL plated car back and forth (several times per year) since 2005 and have never had any issues or more than a couple of questions asked at the border ever.
The trick is, as with anything else, know the rules ahead of time and have all the right answers at the border.
