316L is better than all the above, and you can weld it. Also more expensive. I'd think for car body panels you'd want n50 or n60, but those are marine alloys,

316L is better than all the above, and you can weld it. Also more expensive. I'd think for car body panels you'd want n50 or n60, but those are marine alloys, and they're spendy. It could also be that the material they're using isn't passivated well, in which case the fix is fairly simple (barkeepers friend and a buff wheel).