Analysis on fuel economy and advanced systems of hybrid vehicles

Basic ideas on operation of hybrid vehicles were discussed from a view point of energy saving. Almost double fuel economy of series–parallel–hybrid vehicles was estimated on condition of no engine idling during vehicle stop, energy saving in acceleration using brake energy recovery and high efficiency operation on low load condition using series–hybrid system. From the discussion of overall efficiency, involving fuel cycle, under both low and high load conditions, both series–parallel–hybrid vehicles with internal combustion engine and fuel cell are supposed to have a high potential for the future.