It's not often that car companies show you the real meaning of platform sharing. In the link you will be able to see a video showing the "plateforme 3" that is common to the Peugeot 407 coupe and Citroen C6. Although sharing several components, these cars have very different design and some important technical differences, such as the suspension that is a conventional multilink in the Peugeot and hydropneumatic in the Citroen. And yet, the plateforme is shared and the two cars are built in the same factory.
It might be interesting to watch a similar video for the Audi A3 and Seat Leon. One could find more common parts. Of course, Audi would not make such video since it would be a stupid marketing move. However, a comparison of Audi TT and Golf would be interesting because in this case, although sharing platform, the Audi presents really outstanding features such as the aluminium-steel body..