I walk into the Visitor center at the factory to find that it's not the factory anymore! It's now a showroom, service center and warehouse since September. The very helpful man there explained everything and pointed me towards the new factory just down the road.
I walked into the first sliding glass door but it looked like an employee entrance, so I went out and then into the next door which led me into a big visitor room with floor-to-ceiling glass walls looking right into the factory.
The "factory" is what I would call final assembly, about the size of a basketball court, done this way to reduce the taxes payable for fully assembled cars brought into the country for distribution around Europe. The cars come four to a shipping container, with the wheels bolted onto the hubs so they can roll. The cars enter what is labelled "General Assembly", riding on a smart cart and they move in an S-shaped work line where the car is grabbed from above with a big claw-like hanger. The wheels come off, the battery pack is installed, the drivetrain(s) are installed and then the wheels go back on again. They fill it with windshield washer fluid and then flash the software at which point the car is driveable. The car is lowered onto another smart cart and makes its way to final inspection for paint and water leakage. It comes off the cart and goes through an indoor test track about 900m long with bumps designed to make squeaky things squeak. They then are driven over into the detailing area then parked waiting for shipment though Europe or for local pickup.