The Shotweld process was invented in 1932 at the Edward G. Budd corporation for welding 18/8 autensitic stainless steel without ruining its corrosion resistance, ductility, and fatigue resistance imparted by heat treatment. Shotweld requires accurate control of electrical current level and welding time for each shot. Done properly, it produces a joint stronger than rivets which does not create a hole in the workpiece (source of localized stresses at the hole edges, among other undesirables) and does not require a minimum spacing to avoid loss of strength (imagine the perforations on the edge of a saltine).
Plus, it lends itself to looking really awesome.
Rest assured, though Budd may no longer be making beautiful vehicles using this technique, electric resistance spot welding is still quite alive and well in modern industry, creating durable welded joints in all sorts of metals. The key of course is the regulation of time and amperage.
Properly done, the only way to remove a spot welded joint is to drill through the spot welds. It’s a good way of essentially turning several pieces of sheet metal into one.
Also, can we just take a moment to appreciate the fact that the gutter lip in the photo above has withstood over 30 years of Miami moisture and salt and shows no signs of every wanting to give up? That’s hard core.