Bangle's answer is fabric. So, no metal or aluminium or even plastic panels to make up the body structure, but a movable endoskeleton that supports a fabric skin.
Sounds strange at first, but it's actually path breaking. Using zippers and fasteners to support the skin, the bonnet for instance can open down the centre line by nearly 50 cm in the body bag zipper fashion.
To know more about this amazing car and to view the video of Gina, read on...
Image: Wheels of Gina
Also read:
Let this robot guard your house!