So you are suggesting when Tesla launched this… they had no clue what these things would cost and just plugged a number in to be revised later?Bulleproof glass, a very large amount of a specialized stainless steel, a supremely complex suspension system - these are a few differentiating factors that are costly. As you mentioned production costs rather than capital costs - even amortized to a per-vehicle basis - I'll grant you that we can exclude the immense price of IDRA's casting machine, but the cast frame, even if it pencils out to the same cost as a traditional vehicle's multi-part steel allow frame, still represents a chunk of cost.
So....."not much more" doesn't pass the reality test in my opinion.
Doesn’t pass the WTF test in my opinion.
Tesla had a path to implementing this in the prices they laid out. For the dual motor, the only big/ potentially expensive change since launch was 4WS. Otherwise it makes zero sense for them to launch it the way they did.