Throttle Position During Acceleration and its effect on FE

[MetroMPG]

BSFC plots engine load (throttle input) against fuel consumption, and it's a way to see at what point an engine is producing the most power for the least amount of fuel consumed.

It's a useful thing to know when considering acceleration tactics, but not particularly useful once at cruise (when you want the lowest overall fuel consumption rate, regardless of whether it's the most efficient in terms of power produced per unit of fuel burned).