The only real need for metric is for nuts and bolts and for doing anything scientific. The amount of videos I've seen where some American is talking about his tools and then he wheels out this enormous tray of spanners and sockets, just because he has to double up on everything. The problem is that machines may last +50 years, so even if you stopped now you'd still be lumbering the next couple of generations with buying more tooling than they need. You can do basically everything with a 10mm spanner on European cars. Imperial is more suited for anything where you have to gauge it by eye so fine for food and for carpentry like I know roughly what load a 2x4 can take, I don't need to break that down into more accurate divisions. but Americans doing metal work and going on about, "oh, I'll need to file that down by 3/32...", just stop it... I think you'll probably change your car production over eventually, simply because it would make export sales easier, but if you want to carry on measuring everything else in eagles per doughnut then I guess it doesn't matter that much