if i drive in neutral “N” in slope road without any gas does the car consumes less fuel?

Not really. When you close the throttle on a fuel injected car it automatically reverts to idle mode anyway. You won’t save any fuel putting the gearbox in neutral.

Yes, you can save fuel thsi way, though how much will depend greatly on your driving conditions.

This is part of whats called Hypermilling, here is an article about it

http://www.insideline.com/toyota/prius/hypermilers-breaking-the-100-mpg-barrier.html

Putting an automatic in neutral at a light actually makes it use MORE gas, as it idles FASTER in neutral.

You may save a little gas using neutral on a hill, but you’ll wear the brakes out faster, and it’s easier to replace gas than brakes.

Your wasting time and probably doing some damage to your car, putting it in neutral at traffic lights does not save any gas nor when driving down hill, as Paul said on his answer cars idle higher when in neutral (higher idle means more gas eing used). When driving down hill just take your foot off the gas.

No but in many states you can be ticketed for this, its called (coasting)………..

You won’t save any gas by doing this at lights, but you will save gas by doing it down a hill because the engine won’t be slowing the car down.
However for the same reason you’ll get more brake pad wear when you want to stop and it can be a bit dangerous because you can’t stop as quick and you’ll be more likely to skid without the engine assisting in slowing the car.
The page below tells you how you can change your driving technique to improve fuel economy.