Using DFCO to increase your MPG

[BailOut]

The engine keeps turning because the wheels are turning, which turn the axles, which turn the transmission, which turns the crankshaft, which makes the pistons move.

As stated in the original post the engine becomes a compressor rather than a combustor at this point. Think of it as the drive train operating in reverse... instead of the engine making the wheels turn the wheels are making the engine turn. Since your momentum and the wheels are doing all the work there's no need for the energy that fuel would provide, so the computer turns off the fuel injectors.