Unless I missed something, sounds like they found about a 3 percent efficiency difference. That's promising. Minimal, but it's nice to see porsche putting effort in and fine tuning post-sales even for cars that are approaching 3 years old.
Road tests are a pretty pointless way of doing a real comparison, really.
Lab testing will reveal the real gains in efficiency of the drive train and electrical system and I am sure Porsche are gaining knowledge on the hardware all the time.
I had been surprised they went toi the rear motor from the front but since the rear has a higher gear maybe it runs at a more efficient RPM than the front (both must be turning anyway since there is no clutch).