I see numerous claims about hybrids being more green vehicles than gas only vehicles. Are they really? My wife has a Hyundai Accent that gets 40 mph with her driving measured at pump refills on long highway runs. Can any kind of hybrid beat this kind of highway mileage when fixed charging can not be used? Also how is green ness computed? Seems like how the fixed shore electricity is generated? I would assume solar, water turbine, etc. would be good. I assume coal fired power generation for example would be bad.