On a forum about cars it's in discussion if driving in neutral will get 0 L/100 km or "infinite" MPG. It's been said that when a gear is selected mecanical energy from the wheels will keep the engine running on a steep furface, without using a single drop of fuel...
I'm not getting crazy am I? This is not true, right...??
Agreeing with those that have spoken thus far If it did put fuel in there, you wouldn't be able to engine brake as you do now
Keep in mind that the energy necessary to keep the engine spinning is coming from the momentum your car has -- as SVO said, that momentum is being transfered through the wheels, transmission, etc. and into your engine.
Driving in Neutral, however, will consume however much fuel needed to idle the engine
Time is the best teacher. Unfortunately it kills all its students.