Say you got a sudden red light a few hundred feet in front of you, and you're at speed. No matter what you will have to come to a stop because it's a hella long red. Also allow the condition you want your engine to stay on this whole time--you aren't into EOC and don't want to use the ignition when the light turns green. Finally say if you just coasted in neutral you would still be going very fast when you got to the light.
Under these circumstances the most fuel efficient option is to use DFCO for the longest time possible, using brakes minimally or not at all until you come to a complete stop.
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