Given the high cost of repairs for the aluminium body panels, what would be the weight increase if the body were made of steel or some other composite? (I'm not talking about the underlying structure). What might be the cost differential? Surely, it would make it cheaper to produce and I would think given the already heavy battery packs, I don't think it would be all that much more heavy. Anything that I'm not considering in all of it - forming the shapes, etc?