Originally Posted by
whitesco
Unless I'm badly mistaken they gained weight from additional reinforcements that had to be retrofitted and added to the design.
That was offset by several other savings. For instance they yanked all the wire on the plane and radically reduced the amount of wire and wire bundles needed. Last I heard the excess burn on the 787 was estimated at .09 gal/nm @ 5000nm trip. That still adds up fuel wise, but is extremely competitive.