Ultimate Geek
 

An interesting read, thanks.

So where is the lithium ion battery in the D5?
And how much weight does that magnesium cross bar actually save that meant aluminium was insufficient for the job!

As for the ultra high tensile safety cage, that I sort of get, as it's easier to manipulate strength out of steel alloys than aluminium ones, particularly if you want a small cross section such as the A-pillar.