I've been experimenting with it and it does save a bit of gas, but I think only useful if you're sitting in a traffic jam of some kind for long periods of time.
Separately, driving with Power on Normal and keeping revs to 3k or lower per gear, you can save a good bit of gas. I did an average work week with this style of driving plus Start Stop, I was able to save about 60% on gas vs. normal crazy fast driving
