The Hypercar (shown) achieved 53% curb-mass reduction without compromising safety. Its 14-part structure was much simpler than its typical 100–200 part counterparts made of steel and aluminum. A paper by Oak Ridge National Laboratory drafted a concept of a composite intensive body-in-white with 18 parts. Its concept had over a 60% mass reduction, also with uncompromised safety.
Lovins, A.B. and Rocky Mountain Institute. 1996. Hypercars: Materials, manufacturing, and policy implications. Rocky Mountain Institute. 2 vols.
Boeman, Raymond G., and N. L. Johnson. 2002. Development of a Cost Competitive, Composite Intensive, Body-in-White. Publication 2002-01-1905. Oak Ridge National Laboratory. link
Lovins, Amory B., and David Cramer. 2004. “Hypercars, Hydrogen, and the Automotive Transition.” International Journal of Vehicle Design 35 (1): 50–85. link