I also did some fuel economy testing some time ago using 30 and 40 degrees advance. I did data runs on the same stretch of road back to back only changing the AVCS values. Since I am in Italy and the speed limits around here are 80 and 100 KPH (if they are even followed) I did the tests at 50 and 62 MPH. Here are the screen shots of the results with all the calculations. 40 degrees advance definitely had better fuel economy. I also did a data run at 50 MPH (on a later day though) using an AFR of 15.0 for closed loop fueling.
If you are wondering why I have 5th and 6th gear I will tell you. In a fuel economy thread I read about people claiming our cars will get better fuel economy between 2500 and 3000 RPM vs a lower RPM. In other words, do not cruise at 50 MPH in 6th (2000RPM) instead use 5th (2500RPM). I think I proved that concept completely wrong, as I expected, since 999 times out of 1000 a lower RPM will provide better fuel economy over a higher RPM.