That will continue with only cars made in Canada not having Canadian tariffs. You make 100,000 cars in Canada everything above that amount is subject to tariffs.

The last ~60 years have been a process by which the North American auto industry has been so heavily integrated that there is no such thing as a car made entirely in one country or another, especially in the Detroit–Windsor corridor.

Canada has manufacturers that the US doesn't (and won't for at least 5 years) and vice-versa.