I think it's a symptom of "Tesla = auto upvote on HN" syndrome. If this had been "Ford Focus S Suspension Walkaround" (or "Porche 911", for that matter) I doubt we'd be seeing it on the front page.
I work for a suspension manufacturer in the aftermarket industry for trucks, and a lot of it isn't that extraordinary. The air springs/shock absorber combination that you see there are becoming more normal across wider applications, while already coming equipped on luxury vehicles for quite some time now.
The part that impresses me though is the steering knuckle (they comment on it towards the beginning), and its aluminum hollow construction. We build modified steering knuckles for trucks that provide additional lift height, but out of ductile iron in a cast mold, same as OEM specs/mfg process. So i'm kind of at a loss how they would make it hollowed out, while maintaining stability. Definitely expensive, i know billet aluminum knuckles for corvettes run about $1500/piece.
Basically welding using a combination of joining pressure with a very high speed spinning steel bit that heats the aluminum joint via the friction created by it spinning on its surface. That spinning bit travels along the seam heating, and then it's pushed together when it's no longer quite solid, and spun together by the bit. Some interesting discussion of the crystal structure formed and the associated mechanical properties, as well.
