Re Culzeans comments, I've managed to dig out a bit more info on the engine for the Insight, assuming the Jazz Hybrid installation is the same. I was puzzled why the engine was described in some places as an i-Vtec engine. It turns out Honda are indeed using the i-DSI cylinder head, but also adapted the i-VTEC system to shut all valves during low load cruising and coast mode - Variable Cylinder Management (VCM). As a result the INSIGHT can drive on electric motor only, if driven with a constant speed between 15 and 45 km/h. All valves are shut, the pumping loss is reduced and the recuperation capabilities optimised during coast mode. Presumably the CR-Z uses the i-Vtec system in its usual role of altering the cam profile, so maybe that explains why it doesn't have the electric motor only mode.