I don't think the presses/press lines are (were) the only factor in determining factory car creation capacity. We also have no information about how many car (body) parts Toyota and GM were making and how many were being outsourced when reaching their output capacity, nor how that compares to how many car (body) parts Tesla makes or outsources. I'm not even sure how many car models were being made at Nummi at the height of its production, meaning the more models being made on those presses/press lines the less (differing) parts can be made because of die/die set changes. Having been a press operator before, I know that often times a press/press line can produce far more parts than it/they actually do, but for pesky things like break downs, maintenance, misfeeds, mishits, die changes/set up, bad material, human error, poor scheduling, etc... So I just don't think it's correct (without a lot more information - type of press, cycles (hits per minute), die type, construction (does the die make one part or a pair of parts), and the list goes on) to say that the presses/press lines are limited to 500k cars per year, particularly (again) when Tesla always has the option of adding, never mind becoming more efficient, which is something all factories with presses are constantly working on (and often struggling with).