@zunny: I think there is no harm in driving like that. I use to drive like this while returning from Benjosa, Rawlakot, Swat, Kaghan. Nothing happens, even in nights with headlights ON. Just drive car by shifting gears as you normally do. Yes it can be dangerous when you try this trick on cars that do not have CNG installed. In that case never do this because steering and brakes will be jammed.
@matrix: Engine requires so energy to run, in our cars, fuel energy, whether in form of CNG or Petrol, is major source and it is converted to mechanical energy enabling car to run. In my case I use altitude benefit and use car momentum as fuel. So the car runs as it runs on straight road. I hope this is answer you are looking for.
@hdaackda: The car don't use any sort of fuel in this case as it is in neutral position. The battery is still being charged with alternator as alternator is also working with help of belts which are moving and all engine parts producing power with mechanical energy from car's own momentum. I drive for night hours with lights ON, but no low light. Believe me everything including power steering, brakes, headlights works.
Anyone who tried this or I am the only PakWheeler introducing this idea