The "primer" step for car bodies after they've been welded is (typically) already a dunk tank. Hot dip galvanizing would only be a marginal increase in cost ov

The "primer" step for car bodies after they've been welded is (typically) already a dunk tank. Hot dip galvanizing would only be a marginal increase in cost over that. You can't easily paint over that and people want cars in all sorts of colors and they last "long enough" as-is. Some smaller under-body assemblies are galvanized or zinc plated before paint.