Your answer to the question “Is the 5% between 80 and 85% worth a double-digit tariff?” here is “Yes. A double digit tariff on a car that is 80% made in America makes sense.”
and then there is the other side of the 14.9% coin, which will be fought over by Canada(read ontario), Mexico, China, and the rest
when it comes parts and cars made in Canada and Mexico, that is going to be tricky, as both countrys have historicaly bought a lot of US cars and other stuff, but will now be in no possition to also play along with the anti china stance in the US and tarrifs, and all the other issues at the borders.......geoplotical has more meaning now.