Leave DFCO enabled or disable it

[RSlo]

Have 2016 GT PP. Took to track a couple days ago and when lifting between shifts timing went from 20+ to single digits. Any advantage to disabling it? Or should just leave it. Does it really have that much impact on fuel economy?

[murfie]

From my experience it's a personal preference thing. I drove with out it for three months or so. Found the sound on decel drew more than the already large amount of attention. I lost about 5mph total from 26mpg to 21mpg. That's what the gauge says never actually calculated it since the first tank.

[Bugasu]

I'd say leave it enabled, especially in an emissions testing state.
Ford uses the brief rich period after DFCO (the catalyst reactivation) to calculate a few things for the catalyst monitor. You can see one of their OBDII Theory and Operation guides for an example.