During the production of the car, the workers on the line are actually constantly installing something or other inside the car. That’s why the doors are practically the very last parts to be attached. The doors are fitted complete, with glass, trim and all their electrics. What’s interesting is that the worker uses the manipulator arm to grab the door from the inside, as though he was going to get into the car with it. He fits the doors (the rear doors first) and plugs in the electrical connectors.