“ Any idea how it's efficiency (present and speculative) compares to the Stirling engine? I know they operate at lower temperature differentials,... (read full comment) ” 

Posted on July 29, 2008 at 1:37 PM EDT

“ Why one or the other? Why not both? For that matter, build a motor into the flywheel for a "soft hybrid". See how it stacks up against a... (read full comment) ” 

Posted on August 9, 2007 at 12:31 PM EDT

“ Of course the batteries exist. They are in every hybrid on the street today. Plug in is just larger. A correction to the article: Plug-in hybrid... (read full comment) ” 

Posted on January 8, 2007 at 1:24 PM EST