As for CNG, there are 2 problems:
1) Compressed natural gas engines are very inefficient
2) CNG engines emit more CO2 than gasoline or diesel engines

CNG engines are cleaner, so they emit much less pollution. But for the long term issue of global warming, CNG is worse than what we have today.

But perhaps along the lines you were thinking, remember that the Volt’s ICE runs on gas or E85. Cellulosic ethanol has none of the problems associated with corn ethanol, and can replace up to 35% of our gasoline consumption. See here for details:
http://www.coskata.com/EthanolFeedstockPotential.asp
GM is a major investor in this company.

So if EREV can replace 80%, and cellulosic ethanol can replace 35%, that’s 115% – more than enough to replace all of our current gasoline consumption.

The key problem with that is that it limits the Volt to people who have a garage – or at least a place to plug in, reliably and safely, at night.  How much of the potential market does that eliminate?  If the Volt is expected to appeal to greens… many of them won’t have a garage.

As for the overall tenor of this blog post – Toyota thinks their system is better.  So?

First, let’s consider the history… Toyota has been studying actual Prius operation on the streets for years.  GM?  Not so much.  Who probably has better data?  If the one with better data is saying, "this approach is better," I’d give that possibility some serious consideration.

Second, let’s consider the venue in which Toyota said this… to their stockholders.  They intend to reassure them that they know what they’re doing.  Considering that the Prius actually works, has been on the street for years, is highly reliable and is the fuel economy champ, I’d say… they probably DO know what they’re doing.

GM and its fanboys should spend more time emulating Toyota and less time trying to tear Toyota down.