User blog comment:Matt Hadick/Ultimate Battle Final Round/@comment-11132490-20130710212454/@comment-4738647-20130710230142

Earth trucks don't run on an alien fuel souce called Energon, if robots were made of the same thing Earth trucks are made of they could bearly stand as Steel is too heavy a material.

http://transformers.wikia.com/wiki/Category:MacGuffins

http://transformers.wikia.com/wiki/Category:Substances

There's probably more elements.