I found this article and it mentioned how GM is heading towards saying ok to B20.

I do remember on a bio forum exhanging emails with a GM engineer who worked on medium duty trucks who claimed they tested B20 and gave it a thumbs up.

Also it appears in the second article how GM is looking into Diesel hybrids but mainly for Europe becaue the high cost is not justified here.

B20 article:


http://www.wired.com/news/autotech/0,2554,65054,00.html

Diesel Hybrid:

http://www.wired.com/news/autotech/0,2554,66949,00.html

coming as a literature change soon... I know of no different content in the motors specifically geared towards the higher content bio-fuel.