On another site we are discussing what happens to the engine when the car is coasting down hill. EDIT: We are referring to automatic transmission for the sake of this debate.
One side says that in a modern engine, the injectors shut off all fuel and the reported RPMs are due to the engine spinning strictly through the wheels and transmission 'back powering' the engine.
The other side says an engine needs 4 things to run, fuel, air, compression and ignition, and therefore if the injectors cut off all fuel the engine is considered stalled at that point.
Which do you believe to be correct?