If you've ever side-swiped a curb or accidentally plowed into a gaggle of nuns then you'll know the terrible damage it can do to your bumpers. GM are aiming to reduce car repair costs by introducing shape memory alloys and polymers (so-called "smart materials") which would be able to change their strength, shape and stiffness given certain conditions of heat, stress, magnetic field or electrical voltage. So the Mother Superior might find that landing on your hood is actually like tumbling into a snowdrift of marshmallow, rather than being bludgeoned with a shovel.
It's not just safety and crash-resistant features; how about air-dams and vents that automatically adjust their shape to suit the driving conditions, or interior grab-handles that emerge to help you aboard but then shrink back once the doors are shut.
GM are aiming to have some degree of smart materials in their range by 2010.