From Local Motors comes Strati, 3D printed car printed in layers so you can embed energy-absorbing crash structures or superstrong seat-belt mounts that are anchored deep in the body. You could bond springy bumpers to cushion pedestrian impacts (right now Local is experimenting with a printable elastic polyurethane material called NinjaFlex). And if you managed to catastrophically damage the tub, you could unbolt the motor and suspension, melt the car down, and print a new one. The ultimate recycle.