[fred cook]

The reason that rotary engines are not fuel efficient is because they make little torque at low rpms thus requiring a low axle ratio and excessiver engine speed to start moving the vehicle mass. If the electric motor which develops max torque at stall (0 rpms) is used to start the vehilcle moving perhaps up to 20 mph or so, then the rotary can step in and take over from there. By keeping the engine module lightweight, there will be less mass to accelerate or, the battery pack could be made larger to allow the electrics to work more. With some of the load off the rotary, it could very likely be made to run leaner and thus more efficiently. This would also allow for a more simple catalytic converter to be used. I believe that all of the "issues" could be resolved with some careful engineering.