In my cars, I can coast in neutral for longer than 600m from 90 to 60km/h (0.4 miles from 56 to 37mph).
Aerodynamic deceleration is stronger at 90km/h than at 80, so I will coast longer from 80 to 50km/h (49 to 31mph).
I use coasting in neutral as much as possible and DFCO when I didn't anticipated correctly.
Out of city, DFCO decelerates around 3 times faster than neutral.
In city, DFCO decelerates much more than neutral. Tires pumped up at near max sidewall and coasting in neutral are certainly what permitted me my best improvement

but I have only manual transmissions.
About idle and lean burn, does lean burn is possible at idle or is it only at steady speeds ?
Denis.