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Best BFSC can be easily determined with a vacuum gauge and a tachometer. If you match the dyno proven BSFC by duplicating the RPM and vacuum reading (or conversely the MAP reading) then you are at best BFSC.
It is never at WOT on any modern fuel injected vehicle engine. WOT is floored. If you have enough load on the engine you can get very close to 100% MAP and or 0 Inches of vacuum. It may actually happen at very low throttle position percentages depending on the load applied.
For those who can read vacuum or MAP just use a higher gear at lower speeds and gradually increase the throttle position until you reach full load. Do this at the lowest throttle position possible. When you get the same readings that are repeatable try a lower gear and see if you can do the same thing. The lowest gear that allows you to sustain those parameters will give you best acceleration for the least fuel.
To low a gear and you can not sustain the low vacuum. to high a gear and your acceleration will be to slow to get to the speed desired in a reasonable amount of time.
Find the correct balance and you can make your acceleration as efficient as possible.
I have seen my brothers Prius charging the battery under these circumstances, where the rate of acceleration or cruising would not be sufficient to maintain best bsfc. In those cases the system will charge the battery. Not every time, I guess it depends on the state of charge. I read about the Hyundai Sonata Hybrid doing the same thing.
I does allow some additional electric only operation of the vehicle, where the liquid fuel consumption would be 0.
regards
Mech
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