Few questions for easy, $0.00 modifications

[GasSavers_RoadWarrior]

Because most cars since the early 90s have had injector shutoff above certain RPM when the throttle is closed. Ergo, you could be using more gas idling the motor than letting it engine brake. Also if your tranny doesn't run the pump in neutral (most do) then you might burn the fluid when you put it into neutral when it's warm at highway speed.

IMO in most areas traffic conditions are such that you'll never get to coast very far in neutral anyway, and also aero drag at higher speeds seems to slow you quicker than the motor does, so unless you're in the wide open lonely spaces with straight roads you can see down for miles you'll probably get as much benefit out of the injector cut as you get out of neutral coasting.