Some metals can undergo a bunch of reheats in processing (3D printing of metals is particularly bad) which could approach chemical reduction energy, but you're right to zeroth order (which is good enough in these conversations, IMHO).

Good rule of thumb.

One other point is most automobiles are now recycled. Going what one reads on the internet about 25% of the steel in cars comes from recycled steel. And 95% of cars are fed into the recycling stream when they are scraped.