Not really.  The battery charging from brake energy recapture essentially offsets the extra energy required to haul around all those heavy batteries.   The fuel savings relative to a conventional model (my car is a 2012 Lexus RX-450h) come mainly from an efficient CVT transmission and from the function that causes the gas engine to shut off when coasting or at rest.  Decent savings in the city (10-15%) - almost none on the highway.   And the guy who says the electric engine does most of the work on acceleration is just wrong.  That is when the gas engine is definitely engaged.