Presently I have a BMW E60 530d which failed it's annual inspection due to corrosion around the rear jacking point (which is near the rear subframe mounting point).
Typically ahead of welding (MIG or ARC) I would disconnect the battery to prevent damaging any electrical systems on the vehicle. This particular vehicle has quite a large number of electrical systems including an alarm system which seems able to activate even when the battery is disconnected. Therefore, either specifically to the BMW E60 on generally on modern, computer controlled cars, is there anything else that ought to be disconnected ahead of welding?
As a side thought, I wonder how much would need to be disconnected when welding up a Tesla...