If I remember rightly the C6 concept car had an interesting interior and could seat four with individual chairs and featured amongst other things a bonsai tree {at least at planning stage, stylists drawings}.
Then there was the C-Airlounge with fibre optics running through its interior, really liked the styling of Airlounge hope it influences future models....new Picasso? Also really liked the original Activa concept from 1988....still think this looks quite cool.