Tesla's Gigafactory is set to double the world's battery production, and this week it opened its doors for the first time. Tesla is also working on an electric truck, but Mercedes-Benz beat them to punch this week by launching the world's first all-electric big rig. In other transportation news, a sun-powered airplane completed an epic trip around the world -- and we highlighted eight milestones from its record-shattering flight. Nissan announced that it will give golden Leaf EVs to medal-winning Olympic athletes. And Norway unveiled plans to build the world's first floating underwater traffic tunnels, which will be suspended from pontoons.