Coasting in gear vs coasting in neutral
I've seen many instances where people are talking about coasting in gear versus coasting in neutral and how coasting in gear causes the car to go into this "DFCO" mode where it cuts off the fuel flow to the engine and winds up using less fuel than coasting in neutral. I have to admit that this doesn't make much sense to me. How can an engine running at 2500 rpm be using less fuel than an engine running at 750 rpm? I have trouble believing that the fuel is just "cut off" because, well, the engine is still running. The engine can't run without the combustible material to burn, so it's obviously using fuel. Soooo... can someone help me see the reasoning to people saying that the engine isn't burning any fuel during DFCO?