An article in the October issue of MIT Technology Review [1] stated that only 24% of the energy in gasoline is turned into kinetic energy - the rest is heat. So that simply means that the hydrodgen engine has the same efficiency as the gasoline engine. Unsurprising really. More ramblings on this and similar mis-information from the auto industry in the October issue of Oil IT Journal[2]. [1] http://www.technologyreview.com/ - logon required [2] http://www.oilit.com/corporate/4php/4c_makemonthly.php?year=2008&month=10 "On gas guzzling, CO2, horsepower and 'green' ... "