[ecomodded]

How I find it :
If you are on a very long hill using a kill switch or turning off the ignition is useful while in neutral. I have a hill that I coast for 10km on that I use my kill switch on but not for the 200ft long coast as it passes so quickly that little to no gain can be realized.
In short its a lot of work for a little gain. Most small cars use about 1/3 gal. per hour at idle so that much is possible to be saved with continual obsessive engine off in Neutral coasting.
Using a kill switch(or turning off the key) is a distraction that best left for those purposely long coasts in my opinion.