If load is a factor on fuel flow to the engine, then an engine braking event would put a load on the engine and require fuel to govern it (observe the amount of smoke spewing from decelerating trucks, albeit gearing down intentionally); coasting would at some point cause braking and load the engine; the equilibrium conditions where the crankshaft is in tune with the transmission gear and the tire rotation would be rare indeed in such a dynamic and unstable environment as "driving";

therefore, I maintain that "no fuel" scenarios are idealized, with unknown practical value.