Steel= 1.2
Carbon= 63
More is better!

http://en.wikipedia.org/wiki/Carbon_nanotubes#Strength


"Carbon nanotubes are one of the strongest materials known
to man, both in terms of tensile strength and elastic
modulus. This strength results from the covalent sp2 bonds
formed between the individual carbon atoms. In 2000, an MWNT
was tested to have a tensile strength of 63 GPa [2]. In
comparison, high-carbon steel has a tensile strength of
approximately 1.2 GPa."

Thank you, Buckminster Fuller! Now all we need to do is
bring back the Dymaxion Car!

DSK