The latest in our series of video road tests is America's leading electric motorcycle: the Zero S, from California's Zero Motorcycles. Seventy-five miles per hour and 60 miles between charges are the big numbers here – but how does that translate to real life use? Also, since electricity costs so much less than petrol, can an electric motorcycle be viewed as an economical option? And what about the environment? When the carbon cost of electricity generation is taken into account, how green are electric vehicles? These questions and more, answered after the jump!