Originally Posted by JasonCSU
I think the 6 as a four seat convertible is just too big a car for a folding hard top to work with. It would most likely increase the weight of an already heavy car and consume additional trunk space when stowed compared to the soft top.
This is really the driving issue. The geometry of a folding hardtop is quite complicated and it just doesn't work on a larger coupe with a long, sloping rear window. You can't "clamshell" a roofline like that and leave any trunk.
Convertibles with folding hardtops invariably compromise one way or another:
1) They start with a small cabin space and shallow windows above the doorline (Mercedes SLK, BMW Z4, etc.)
2) They take an existing coupe roofline and pinch/shorten the length of the rear window slope (example: 3 Series) to form an easy break point.
3) They raise the trunk to make more room for the folded roof (Lexus IS, Infiniti G)
The Lexus IS convertible looks terrible for this reason and the Infiniti G isn't much better. BMW at least made the right compromise with the 3 Series convertible. Folding hard tops are here to stay because they sell to people who want the best (in their eyes) of both worlds. Maybe someone will find an elegant way of folding a long coupe roofline into more pieces without looking terrible, but until that time, the 6 Series and A5 will have to stay soft top.