I think they still have a significant lead in actual production manufacturing engineering. It's one of the primary things they do, and have some of the best minds in the world for it. I think Tesla can catch up, but right now Tesla has a very outmoded plant itself, its a former GM plant built in the 60's and rebuilt for NUMI in the 80's. While they're building new ones, a majority of the big three's plants date from 1980-2005, and are newer in structure.

If you talk about how cars are built, all auto manufactures seem to follow the same basic model to build cars, robotic welded bodies, a mix of manual and robotic paint and a moving assembly line to put the rest on - everyone does it the same way with some minor variations. Similarly Toyotas JIT supply system is used the world over by all auto manufacturers because it improves the balance sheet.