Bring up the Loop gauge. If it shows Open Loop in that case, you are indeed using no fuel.
(DFCO - decelleration Fuel Cut Off)
There's a time for that, and there's a time for coasting in neutral. DFCO trades zero fuel usage for a shorter glide distance. You have to weight the situation to see what's best. Generally, it's better to coast in neutral, because of the longer glide distance. If you're having to stop anyway, use DFCO.