I don't know if this has been answered long ago, but just out of curiosity, I remember reading that the 918 concept was supposed to weight below 3200lbs even with a 160kw battery and motor setup, but what happened to it that made it go up about 500lbs?  In case you're wondering where I'm getting that from : 1

It exceeded all the planned specs by 15 - 20%. Including weight.