[comptiger5000]

This is true. More throttle generally puts the engine in a more efficient portion of its load curve, so it takes less fuel to get the same total work output, just over a shorter period of time. Of course, with an automatic, there's a point above which gassing it harder only makes it shift way too late, bringing FE back down. The challenge is finding the sweet spot. With a stick, you can run 70% throttle and still shift early, giving more benefit from this.