First, it's great to see people relating the readings to each other. Integrating ideas from multiple authors is essential to thinking critically about the material we are covering. It also shows that you've been interacting with the ideas in the texts rather than simply taking them at face value.
In response to the comment about primitivism and hybrid cars, that's in interesting paradox. I don't think Marx intended that the three philosophies be mutually exclusive; one person may have to reconcile both progressive and primitivist desires (I know I do...). That said, on p. 462, Marx says that primitivists would view fewer "interventions of science-based technology" as better, so this may place hybrid cars and other more environmentally friendly technologies in the progressive category. Although, not neatly.
A while back, there was a question about the cover art. On the back cover, there's a little blurb about the figure on the front, which could be a launching point for some independent discovery.
With respect to Pan's Travail, I noticed a strong theme of balance throughout the book. Hughes attributes the longevity and prosperity of a society to its ability to stay in balance with nature. I originally thought that this would be like trying to find a root cause for the collapse of ancient civilizations (i.e. brought on by society falling out of balance with nature), but Hughes considers many factors in his notion of balance. It isn't only over-population, only pollution, deforestation, or erosion, but the combined effects of these phenomena that led to environmental degradation and the fall of ancient civilizations. Also, did anyone else detect some primitivist ideals in Hughes description of the Paleolithic and Neolithic people? Even though he pointed out some environmental problems faced by these ancient societies, the overwhelming impression that Hughes left was that these people loved and respected nature and had a oneness unlike that experienced in later civilizations. I would have imagined that a group of people more exposed to the harshness of life without the comforts of civilizations would have had some contempt for the difficulties posed by nature intermingled with their love.