[Daschicken]

In your situation, yes it is more efficient to leave it in gear assuming you have DFCO. You need to learn your car, and learn to predict situations of where to use DFCO and where to coast. Some cars you can feel it, some you can't. I can feel it with mine. If you have a car with ridiculously noisy fuel injectors, like my dad's Merc, then yes, you can also hear it. Otherwise, don't expect to.

Kind of backwards, but high performance and high revving vehicles such as my dad's VFR 800 and S2000 have DFCO that is available RIGHT AWAY, and I think down to 1500 RPM(VFR). Don't have more information about this since it's been a while since I have ridden the VFR, I prefer my CBR.

My car doesn't get DFCO until it hits about 140-150 degrees Fahrenheit, I have to be around 1300 rpm or above for it to initiate. My car maintains DFCO down to 950 RPM when warm, and down to I think around 1100-1200 RPM when warming up. It usually lurches out of DFCO abruptly because I don't expect it to back out that early.

Accord(HA!)ing to my service manual, the auto version of my car gets another 100 RPM of DFCO, cutting out at 850 instead of 950.