My 2014 Mazda CX-5 GT (automatic) cuts off fuel as soon as I let off the gas (on highway), but the torque converter is still locked, so in effect, it will engine brake and slow down my car more than I want it to. It's okay on downhills where I would need to slow down anyways, but not so good on flats. It would be a better approach if I could choose to let it just idle (using some gas) and disengage torque converter, which is like putting gear in N while coasting.

I read in a 2014 Mini Hardtop user manual, they do exactly this in Green Mode. When speed is above 30 MPH, and you let go the throttle, torque converter is disengaged and engine goes idle (uses some gas) while gliding, same as putting in N.

So I guess it varies by manufacturer how they implement the gas paddle off situation.

That's another reason I hate auto's, you just can't drive the way you want to drive. I use neutral a lot around here.

Manual transmissions will DFCO too.

I appreciate that, its just easier to coast in neutral in a manual.