AllenF — I'll try one last time! You can't get something for nothing. All the electrical energy that the electric motor uses (included regenerated energy from braking) can be traced back to energy originally produced by the ICE from burning gasoline. Having a very efficient electric motor can't overcome the fact that the electrical energy it uses has already been subject to losses in the ICE (and also the battery, if involved) — all it can do is reduce the extent of the further energy loss. There's no perpetual motion machine; the laws of physics are immutable! Yes, running the ICE at low power will burn less fuel, but it will also correspondingly do less work! Its efficiency could also drop by a factor of two! The demand on the vehicle will dictate moment by moment the work that the ICE needs to do. And the work that it does will use more gasoline per kWh of work done if it's run inefficiently. The whole science of hybrid ECU programming is to maximize the moment by moment efficiency of the ICE, within the limits imposed by the parameters of the system.

Stan