My car had folding mirrors from the factory and didn't fold when locked - I didn't even have the convienence menu in the cluster, it has now tho!
afaik some C - Class w203's didn't have folding mirrors on lock as standard, you could only fold them by pressing the button next to the headlight switch.
If i'm correct if you press the button once and it folds then you can have folding on lock - as opposed to having to hold the fold button in until the mirror has folded. and also depending if the SAM can accept the programming