Great thread. I know they make a device that measures watts of power at the crank or drive wheel. Pro bikers use this to measure performance.
Cycling power meter - Wikipedia, the free encyclopedia
I used to do endurance cycling events 200 miles in a days. And I noticed that body position is more important than anything else. Even experimented with sitting upright and twisting my body to align with wind direction. This helped greatly on coasting further.
Good luck with your testing.