I did a careful distance test today. My bike is a DIY short wheel base recumbent. 26in rear MP1 with Schwalbe big apple pumped to 60psi. Batteries 16S 10ah headways.
Cycle analyst says 7.7wh/km after 45km. I was using the cruise control and running at 30kmh. It was really ideal conditions with hardly any hill or wind. Still I am really impressed with the efficiency. 
Cheers
Stan
I think BLDC is awesome but where the Pie gets its efficiency is the large surface area of the housing makes for very low heat accumulation so the resistance of the windings stays low always.
Another reason is the large diameter stator has good effect on the poles so the magnetic intensity does not collapse as easy so the force is translated to the torque more on take off and hills. Meaning you get more power for what you put in. Bang for buck.
The smaller diameter hubs makes more noise maybe on take offs, you can hear the load break the force off the magnet poles during heavy load times.
Thanks for sharing.
