The die-castings are almost certainly aluminum. Possibly A380 or something similar. The stamped side pieces might be aluminum but I would bet they are actually steel. Nowadays dissimilar materials can be joined together using rivets and panel bonding ahesive.
From a mechanical layout perspective, this configuration makes no sense. It requires a transfer case and drive shaft somewhere between the two axles. That space is used by the battery modules. I can see an entry level model having single motor with RWD. If you want AWD, it will (at least) be...