Since we are all just guessing, my speculation is that the X Falcon Wings cost significantly more to make than the S rear doors (highly likely), the auto opening X front doors cost more, the X windshield costs more, the X second row pedestal seats cost more, the X air purification system costs more (nothing comparable yet for the S), base 20" Cyclone wheels cost more than S base wheels, and who knows what else.
So I agree with those that say a "comparably equipped" S probably includes options like the pano roof and rear child seats.
If Tesla can get acceptable margins on a base X that is only $5K more expensive than a truly "base" S (with no options) then my hat is off to them! If I wore a hat...[emoji6]
Let's assume the 5k difference captures everything in it about the car being "larger", to that end, that would be slightly more overall glass, and slightly more aluminum, more lining and things like that.
Focusing in specifically, and we are just talking about manufacturing cost right? Looking at the Rear doors, instead of stamping one main piece for each door, and then one piece for the roof, they just need to stamp two pieces for the rear doors which intrude into the same amount of alluminum (other than the overall size increase of the X itself). I would think that overall glass coverage is roughly the same between the cars, although they are certainly different pieces all around. the lining and such would cost roughly the same. So we are talking about one extra hinge (well two for each side of the door, which is four extra brackets), and the extra wiring to make them lift (probably similar to the power lift gate, only the computer again is able to control two different moveable parts instead of just one) so however much that costs, although the rear handles don't come out (at least I don't think they do) so maybe that helps save something... There is also the cost of the "hidden" sensors in the door. So I wouldn't picture from a component cost that we are talking all that much of a difference here, other than largely being captured in it being a bigger vehicle. Resource cost, is it more difficult to put together in the factory? By this I mean, does it take more time to install? I ask since the employees would be paid by the hour (or robots running certain volumes through), so if the time for assembly of piecing these together greatly exceeds the time of the Model S, then there would be an increased cost here. What I don't care about here is R&D cost to program the doors, and make them altogether work as this is a non-factor in the GM and would be cut and paste from one to the next. So what is "significantly more"? Because assuming it doesn't take them longer to assemble the X over the S (even if the doors themselves take a bit longer, it may balance out over the whole line with minor improvements, say, in not needing to attach a nose cone) then I don't think the raw component cost would be all that significant.
The auto doors, there is no reason for them not to stick this on the S, and we don't know if they will wrap this into a package or include it in the base. It could be like the power lift gate where it is in the cost of the premium interior, and presumably there is no logical reason not to make this part of the S at some point.
Same with the air filter. Is there any technical reason they couldn't make some modifications to the S to add in the bigger and better filter?
As for the 20" wheels I am torn on this one, I could see this going either way, where they aren't charging anything more for it, and this too is included in that "5k" price difference.
Not saying anything you said is wrong, just trying to analyze and over-analyze the question to figure out where the line gets drawn. Whatever the base ends up at, I am certain Tesla won't sacrifice margins for it. Especially given the demand for the vehicle.