Was bored, so I played around with my Apexi throttle controller on the IS-F today.
Generally, I get 10.2L/100km when I drive "normal" during my commute to work.
I decided to put it into the least exciting mode to see what, if any, it would do to fuel mileage. Surprisingly, it returned 8.6L/100km during the same trip. So the electronic trickery works. But man...it feel like I was towing a boat anchor.
For those who care, here are the modes as compared to stock and a photo of the stock looking install.