I do not really understand why people would be irked if they have to wait in line. I am not addressing anyone in particular, but we now know that Tesla is delivering P90Ds first. For the Every 4 or 5 P90Ds that Tesla delivers, it can show the same profit of an additional Model X without having had to produce it. Of course it is not only about profit, but also about total number of vehicles delivered with as few problems as possible. I ordered a 90D because I feel I do not need the Performance package. If you go to the store, do you expect to be checked out first if you buy more stuff. It does not work that way. First come first served. If you go to the bank, do you get to jump the line if you have a larger deposit that the other people? No, it does not work that way. First come first served. Tesla never said that they will produce all of the P90Ds first before they start with 90Ds. At some point they have to draw a line and start producing both, because people will continue to order the P90Ds while others have waited for nearly 4 years. I decided in February of 2012 that I wanted a Model X, and that I will get the one with the largest available battery pack, but I did not reserve until a few months later, after I decided not to go with a sig, but just a standard production model. I too sometimes feel like I am getting irked, but the fact of the matter is that we have all waited a long time, and some.
Another point that needs to be made is that Tesla initially built a production line to spit out Signature Xs. It would make logical sense (to me) that once they have that running smoothly, they can start to make alterations to the line to add new options/features. I would imagine that trying to build all combinations from day one would be a recipe for disaster.
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Or what jsollender wrote, as he/she beat me to it.