I noticed, upon taking delivery of my 90d this past monday, that the overall alignment of panels is piss poor. This is an indicator of build quality someone pointed out to me decades ago when American cars had huge, variable gaps but Japanese and German cars had small, uniformly consistent, perfect gaps between panels and perfect edge alignment. These days, I notice that American cars, having significantly improved their quality, demonstrate these smaller tolerances and better alignment details. It's funny that you mentioned your wife's X5 because one thing that has bothered me about my x5 is that the automaticity closing/latching doors (they only close the last little bit) do not sit flush. But this is not an alignment issue, it's a symptom of the mechanism that closes the door. I would have preferred a flush door that I had to close more forcefully.
On the other hand, when I drive my ModelS, there are no squeaks or rattles, no pulls, no shimmies, no clicks, no hesitation, no screen boot errors, no door lock fails, no tire pressure monitor malfunctions, no engine stalls
, no turbo lag, no traction control interference, etc. The car is incredibly tight and amazing to drive and experience.
So to consider the contrast between panel alignment and the actual demonstration of quality that driving provides, I form the hypothesis that we are driving the equivalent of a hand built car. The quality is dripping from the thing but, as it is the very first production model from a brand new car company, tolerances are not yet dialed in. It's just a hypothesis, not even a theory, but it's much like the denting frunk... You don't see these issues until you've sent 100,000 of them out into the world. So, like a hand built car, the builder should take care of his customers and fix the inconsistencies.
My point is that I agree that panel and edge alignment on a car are typically an indicator of overall build quality but, in isolation, it is just one issue that could be improved.