Most cars and trucks when coasting just uncouple the trans but must maintain fuel to idle the engine
thats wrong, If it is so, u cannot drive a hill down with Enginebrake.
When i drive a Hill down, there is nothing which uncouple.
The Transmission stays in the selected Gear, the only Option i have, ist to select a lower gear, for more Engine-Brake.
Or select Neutral. (Not good while coasting Downhill)
(With Automatic Transmission, shifting to N while driving downhill, can Kill the Transmission. I will never do that. )
I know no Car which have no DFCO except my 2000 f150 Truck.
Also my S80 Auto trans Volvo has DFCO
My Old Manual WV Golf has DFCO
My selled Audi's (Diesel and Gasoline) had DFCO