Sorry but I do not agree with your analysis. If all the cars we buy would be designed and build in Canada, your comparison with Jamaica would work. But we already import most of our cars.
And I did point that out. My example of Jamaica was dealing with the blanket statement that "free trade" is always preferable. That nation is one example (of many) where opening their borders did much greater harm than good.
As to the specific example of cars, yes I did acknowledge that thanks to the low numbers of Canadian made cars, the decision comes down to really who do we effect by buying in the US, and there is no clear winner/loser and that includes the Canadian Subaru dealer, as they may even reap benefits from a greater Subaru population thanks to their true profit center: the service department.
What we had was two positions, one presented by Snowie, one by Guy. One said simply "buy locally and support your nation." The other was "nope, free trade is always the best way."
Both of those positions are too simplistic and frankly, incorrect without much further explantion.