I had one of the early (2003) Citroen C5's, and when it was actaully working, it was as fine a tow car as anything that I know of. Citroen filled the thing with toy's though, and this was it's Achilles heel - the electronic's on these 'extra's' were a constant scource of trouble and it was repeatedly in and out of the Dealer's. It would seem to me that Citroen have some fine ideas, but we are used as the test bed for them! I feel quite certain that the present day C5 is a good, reliable car, but if the system that you are considering on the C4 is anything other than very well proven, steer well clear!