You could start me on the environmental impact of cars which of course are subject to much legislation in a similar vein. The Prius is touted as the environmentally friendly car to drive but if you analyse it's whole life impact 'cradle to grave' then it is worse for this planet than many 'ordinary' cars. I have read that a study showed that the 'Hummer' over it's life taking into account manufacture, emissions, and disposal is more environmentally friendly than a Prius.