Mazda is now the proud producer or the world's lightest bumpers!

Mazda has announced a new resin material that will use to make the world's lightest bumpers.
Jointly developed with the Japan Polypropylene Corporation, the resin maintains the same rigidity as parts made with conventional materials, but the parts are thinner and require less material. When both front and rear bumpers are made from the resin, the weight reduction is approximately 20 percent.

http://www.autos.ca/general-news/mazda-designs-worlds-lightest-bumpers