During the Sixties the European car makers made extensive use of the steel unibody: at the end of the decade they were able to develop the first internal standards and procedures.

In the meantime several researches were performed investigating the use of alternative materials, mainly the new emerging composites.

Lotus Elan - Backbone chassis

In 1962 Lotus lunched the Elan, with a so called Backbone Chassis (see Figure), a frame made by a central steel load-bearing hollow element that supported the engine and the suspension and contained the trasmission.
The body panels were in fiberglass and connected to the frame with structural adhesives.

In 1963-64 in Italy several city cars with unibody structures that used fiberglass reinforced plastics were launched: the Autobianchi Stellina, the ASA 1000 Spyder, the LMX, S.S. 100, the Bagheera.

In 1967 Bayer built an experimental vehicle with load-bearing plastics body that made use of "sandwich panels", with two glass-fiber reinforced plastic layers and one polyurethane foam inner layer.

In the USA the Body-on-Frame solution was still the most adopted structure for production cars.