Well let's think through a conventional truck frame. It's maybe 800-1200 lbs, uses 3-8 different materials, and has 100-200 fastening points and all those mater

Well let's think through a conventional truck frame. It's maybe 800-1200 lbs, uses 3-8 different materials, and has 100-200 fastening points and all those materials probably cost nearly as much as stainless steel. And remember, the cost of an automobile isn't just the material cost, you have to amortize the manufacturing plant and the paint shop. By stressing the stainless steel skin (like an aircraft), Tesla doesn't really need to buy additional material, but they simplify the manufacturing dramatically because they don't need a paint shop and they don't need to assemble a frame.