Assuming the opening poster is correct about EFI, which I believe he is, it saves fuel to drift in gear as long as there is enough of a downslope to prevent the car from decelerating. It also saves fuel to keep the engine in gear when a stop can be anticipated and a gradual deceleration is acceptable.

I doubt that it provides a significant benefit, but I attempt to do take advantage of this. When I am going down a long mountain decline I keep the car in the gear that is necessary to maintain approximately a constant speed. This saves brakes and cuts fuel consumption to zero. When I am coming to a stop that I can anticipate early I let the engine resistance slow the car down gradually and finally I will drift forward with the car in neutral when the car is moving to slow to keep the engine alive.