Gas Mileage Questions

The vast majority newer EFI cars shut the injectors off entirely during decel after the coolant temp is above a certain point. There is a very slight delay before this happens as hotrodkid said. Fuel kicks back on when rpms fall below a certain point so the car can fall gracefully to idle without stumbling or stalling.

As zerodaze pointed out to keep the engine going without moving in gear obviously fuel is required. On some EFI cars they do spray fuel on decel…just a very small amount.

edit: I know on newer performance oriented Honda/Acura vehicles they throw a good amount of fuel on decel to keep the cat from failing.