[jtheory]

Purchasers of the Z1 probably wouldn't be worrying about the problems of added moving parts requiring more (or more expensive) maintanance.

But this (from the wiki page) was interesting:

"The windows may be operated independently of the doors, although they do retract automatically if the door is lowered. Both the window and door are driven by electric motors through toothed rubber belts and may be moved manually in an emergency.[6]"

That could apply to any installation of this kind of door, actually -- if your battery is dead, you have to use a keyhole to unlock the door, then you could manually push down the window & then door structure. If they are well counter-balanced with weights or springs, etc. (as they should be to avoid wasting energy in normal use) and the motor doesn't cause much drag, that would be a bit awkward-looking, but not too hard.

[jnhnum1]

Not true - in general, the reason you can't push down car windows is because they're driven via a worm gear to increase the force exerted by the motor, but you can't back-drive a worm gear.

[jtheory]

I was pointing out that it was interesting that in the car that was actually produced with this type of door, they used belts (instead of the worm gear you're talking about) so that the door could be manually opened.

This is probably the approach that any other mass-produced version of this door would take as well -- avoiding the worm gear so that the window & door could be manually moved if needed.

That addresses the main concerns people had.