The only thing that appeals to me about sustainable transportation options is that they are sustainable by this definition: Any form of transport that does not use or rely on dwindling natural resources. Instead it relies on renewable or regenerated energy rather than fossil fuel that have a finite life. I think future generations will be grateful to those that adopt the philosophy and supported the technology to make it happen. I think we need ICE, hybrid, and PEV options. Drive what you like, Like what you drive.