Having looked around the factory at Ingolstadt and seen A3s being built, all the painted components for a particular car are sprayed at the same time, but then go off to different storage areas and then come together again for final assemby.
Computers control the supply of the correct parts and components to the production line for the guys to actually fit in the cars. As the lines produce cars of varying colour, models and for different markets, 3-doors and Sportbacks one after the other on the line is great to see all the different 'bits' coming together.
When I last visted Ingolstadt, my wife and I had booked a tour with a english-speaking guide. He was quite happy to spend all afternoon with us just walking around and explaining everthing. What is normally a 2 hour tour ended up being nearly 4 hours.
The plant in Brussels made some A3s between autumn 2004 and the end of 2005 and now they will produces around 30,000 cars a year. Towards the end of 2009 they will start production of the new A1 which will be built exclusively at Brussels.