The topic is quite interesting to me. Hybrid systems seem to be chasing better fuel economy by making a more complicated drive train. Dig a bit deeper and the heart of hybrid is some form of Atkinson/Miller cycle ICE. Nothing seems to be more despised by NAT'ers, than variable valve actuators on a gas engine but that's what makes a Miller Cycle engine. Of course, the idle stop/go is also found in hybrids and that feature doesn't seem to be too popular either.