At zero throttle, above 1000RPM, all fuel is cut from the engine. So while descending a hill in gear you will be using NO fuel. Idling the engine will of course burn fuel.Double-Trinity said:Not necessarily... if the downhill is a gradual descent, then the engine braking often requires more gas to overcome than running the engine at idle. I'm not sure about this, but it seems like it would be possible for the car to be charging when in neutral for this reason: since the motor and engine are connected to one another, the motor could harness some of the power from the idling engine... I've
never seen that behavior on my IMA civic, though.