It's only incredible engineering once it performs in the hands of buyers. It's an incredible demo until then.
The software industry has taught me how sneaky a demo can be ;). That's without considering Tesla's history of bonkers claims and sus demos (anyone else remember the bulletproof windows?).
Edit: Removed a rhetorical question about the demo. Apparently there was a live audience, so they couldn't have just made a very tiny Roadster haha.
But you know, that's just off the top of my head.
Based on the record of Musk & co straight out LYING in such events (remember Solarcity?), I am very confident in saying that a large portion of what they demonstrated they have not actually solved how to fit in a real production car.
They could be in the unit when its happening and there would still be some counterclaim.
It's amazing how on HN, a place where hackers, dreamers, builders come together to talk can't say one positive thing from some of these actual delivered engineering feats. It's bias happening real-time.