[peregrine falcon]

I don't see how downshifting gears(I'm talking manually and abruptly) to slow down would be any better on gas than using brakes. I know if you just let off the gas and let the engine slow u down its better on gas as opposed to staying at speed then stopping fast with either brake or downshifting, because the greater the distance you slow down the greater the mileage will be since for that distance your using very little gas.

I think the more you use natural forces(wind, atmospheric friction) to stop the better the mileage will be